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UNCLASSIFIED 



cr/6 


UNCLASSIFIED 



SUMMARY TECHNICAL REPORT 
OF THE 

NATIONAL DEFENSE RESEARCH COMMITTEE 


This document contains information affecting the national defense of the United 
States within the meaning of the Espionage Act, 50 U. S. C., 31 and 32, as amended. 
Its transmission or the revelation of its contents in any manner to an unauthor¬ 
ized person is prohibited by law. 

I bis volume is classified CONFIDENTIAL in accordance with security regula¬ 
tions of the War and Navy Departments because certain chapters contain mate¬ 
rial which was CONFIDENTIAL at the date of printing. Other chapters may 
have had a lower classification or none. The reader is advised to consult the War 
and Navy agencies listed on the reverse of this page for the current classification 
of any material. 






Manuscript and illustrations for this volume were prepared for 
publication by the Summary Reports Group of the Columbia 
University Division of War Research under contract OEMsr-1131 
with the Office of Scientific Research and Development. This vol¬ 
ume was printed and bound by the Columbia University Press. 

Distribution of the Summary Technical Report of N I)RC has been 
made by the War and Navy Departments. Inquiries concerning the 
availability and distribution of the Summary Technical Report 
volumes and microfilmed and other reference material should be 
addressed to the War Department Library, Room 1A-522, The 
Pentagon, Washington 25, D. C., or to the Office of Naval Research, 
Navy Department, Attention: Reports and Documents Section, 
Washington 25, D. C. 


Copy No. 




SUMMARY TECHNICAL REPORT OF DIVISION 12, NDRC 


VOLUME I 


TRANSPORTATION EQUIPMENT 
AND RELATED PROBLEMS 


OFFICE OF SCIENTIFIC RESEARCH AND DEVELOPMENT 

VANNEVAR BUSH, DIRECTOR 

NATIONAL DEFENSE RESEARCH COMMITTEE 
JAMES B. CONANT, CHAIRMAN 

DIVISION 12 

HARTLEY ROWE, CHIEF 


WASHINGTON, D. C., 1946 






NATIONAL DEFENSE RESEARCH COMMITTEE 


James B. Conant, Chairman 
Richard C.Tolman, Vice Chairman 
Roger Adams Army Representative 1 

Frank B. Jewett Navy Representative 2 

Karl T. Compton Commissioner of Patents 3 

Irvin Stewart, Executive Secretary 


1 Army representatives in order of service: 

Maj. Gen. G. V. Strong Col. L. A. Denson 

Maj. Gen. R. C. Moore Col. P. R. Faymonville 

Maj. Gen. C. C. Williams Brig. Gen. E. A. Regnier 
Brig. Gen. W. A. Wood, Jr. Col. M. M. Irvine 
Col. E. A. Routheau 


2 Navy representatives in order of service: 

Rear Adm. H. G. Bowen Rear Adm. J. A. Furer 

Capt. Lybrand P. Smith Rear Adm. A. H. Van Keuren 

Commodore H. A. Schade 
3 Commissioners of Patents in order of service: 
Conway P. Coe Casper W. Ooms 


NOTES ON THE ORGANIZATION OF NDRC 


The duties of the National Defense Research Committee 
were (1) to recommend to the Director of OSRD suitable 
projects and research programs on the instrumentalities of 
warfare, together with contract facilities for carrying out 
these projects and programs, and (2) to administer the tech¬ 
nical and scientific work of the contracts. More specifically, 
NDRC functioned by initiating research projects on re¬ 
quests from the Army or the Navy, or on requests from an 
allied government transmitted through the Liaison Office 
of OSRD, or on its own considered initiative as a result of 
the experience of its members. Proposals prepared by the 
Division, Panel, or Committee for research contracts for 
performance of the work involved in such projects were 
first reviewed by NDRC, and if approved, recommended to 
the Director of OSRD. Upon approval of a proposal by the 
Director, a contract permitting maximum flexibility of 
scientific effort was arranged. The business aspects of the 
contract, including such matters as materials, clearances, 
vouchers, patents, priorities, legal matters, and administra¬ 
tion of patent matters were handled by the Executive Sec¬ 
retary of OSRD. 

Originally NDRC administered its work through five 
divisions, each headed by one of the NDRC members. 
These were: 

Division A —Armor and Ordnance 
Division B — Bombs, Fuels, Gases, & Chemical Problems 
Division C — Communication and Transportation 
Division D —Detection, Controls, and Instruments 
Division E — Patents and Inventions 


In a reorganization in the fall of 1942, twenty-three ad¬ 
ministrative divisions, panels, or committees were created, 
each with a chief selected on the basis of his outstanding 
work in the particular field. The NDRC members then be¬ 
came a reviewing and advisory group to the Director of 
OSRD. The final organization was as follows: 


Division 1 — Ballistic Research 

Division 2 — Effects of Impact and Explosion 

Division 3 — Rocket Ordnance 

Division 4 — Ordnance Accessories 

Division 5 — New Missiles 

Division 6 —Sub-Surface Warfare 

Division 7 — Fire Control 

Division 8 — Explosives 

Division 9 — Chemistry 

Division 10 —Absorbents and Aerosols 

Division 11 — Chemical Engineering 

Division 12 —Transportation 

Division 13 — Electrical Communication 

Division 14 —Radar 

Division 15 — Radio Coordination 

Division 16 — Optics and Camouflage 

Division 17 — Physics 

Division 18 — War Metallurgy 

Division 19 —Miscellaneous 

Applied Mathematics Panel 

Applied Psychology Panel 

Committee on Propagation 

Tropical Deterioration Administrative Committee 


iv 



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490936 




















NDRC FOREWORD 


as events of the years preceding 1940 revealed more 
41 and more clearly the seriousness of the world 
situation, many scientists in this country came to 
realize the need of organizing scientific research for 
service in a national emergency. Recommendations 
which they made to the White House were given care¬ 
ful and sympathetic attention, and as a result the 
National Defense Research Committee [NDRC] was 
formed by Executive Order of the President in the 
summer of 1940. The members of NDRC, appointed 
by the President, were instructed to supplement the 
work of the Army and the Navy in the development 
of the instrumentalities of war. A year later, upon the 
establishment of the Office of Scientific Research and 
Development [OSRD], NDRC became one of its 
units. 

The Summary Technical Report of NDRC is a con¬ 
scientious effort on the part of NDRC to summarize 
and evaluate its work and to present it in a useful and 
permanent form. It comprises some seventy volumes 
broken into groups corresponding to the NDRC Divi¬ 
sions, Panels, and Committees. 

The Summary Technical Report of each Division, 
Panel, or Committee is an integral survey of the work 
of that group. The first volume of each group’s re¬ 
port contains a summary of the report, stating the 
problems presented and the philosophy of attacking 
them, and summarizing the results of the research, de¬ 
velopment, and training activities undertaken. Some 
volumes may be “state of the art” treatises covering 
subjects to which various research groups have con¬ 
tributed information. Others may contain descrip¬ 
tions of devices developed in the laboratories. A mas¬ 
ter index of all these divisional, panel, and committee 
reports which together constitute the Summary Tech¬ 
nical Report of NDRC is contained in a separate vol¬ 
ume, which also includes the index of a microfilm 
record of pertinent technical laboratory reports and 
reference material. 

Some of the NDRC-sponsored researches which 
had been declassified by the end of 1945 were of suffi¬ 
cient popular interest that it was found desirable to 
report them in the form of monographs, such as the 
series on radar by Division 14 and the monograph on 


sampling inspection by the Applied Mathematics 
Panel. Since the material treated in them is not dupli¬ 
cated in the Summary Technical Report of NDRC, 
the monographs are an important part of the story of 
these aspects of NDRC research. 

In contrast to the information on radar, which is of 
widespread interest and much of which is released to 
the public, the research on subsurface warfare is 
largely classified and is of general interest to a more 
restricted group. As a consecjuence, the report of Divi¬ 
sion 6 is found almost entirely in its Summary Tech¬ 
nical Report, which runs to over twenty volumes. The 
extent of the work of a division cannot therefore be 
judged solely by the number of volumes devoted to it 
in the Summary Technical Report of NDRC: account 
must be taken of the monographs and available re¬ 
ports published elsewhere. 

Division 12 was one of the smallest divisions of 
NDRC, but its accomplishments were far out of pro¬ 
portion to its size and its impact on the conduct of 
the war was of major significance. Battle reports from 
Normandy to Okinawa attest to the value of its con¬ 
tributions to the concept and the implementation of 
amphibious logistics and of the amphibious assault. 
These reports serve likewise as testimonials to the 
vision, the intense personal devotion, and the integ¬ 
rity of Hartley L. Rowe, Chief of the Division, and of 
the men who worked on his staff and on the staff of 
the Division’s contractors. 

This volume, the Summary Technical Report of 
Division 12, was prepared under the direction of the 
Division Chief and authorized by him for publication. 
It presents the methods and results of the Division’s 
technical activities. In addition, however, it is the rec¬ 
ord of a group of men who contributed loyally to the 
defense of their country. They were few in number. 
Without their efforts, the course of the war might 
have been far different. To them all goes our sincere 
gratitude. 

Vannevar Bush, Director 
Office of Scieyitific Research and Development 

J. B. Conant, Chairman 
National Defense Research Committee 




v 































FOREWORD 


I n world war ii the tree peoples of the Western 
democracies appear to have waged a more work¬ 
manlike total war than did the total States of our 
enemies. 

Our over all planning was better, our mobilization 
more effective. And. although German technical su¬ 
periority, particularly in certain ordnance items, per¬ 
sisted to V-E day, it is probably true that our over all 
accomplishment in the development of new weapons 
surpassed that of our enemies. Our loose-jointed 
democratic military organizations permitted the flow 
of new ideas, while the close-coupled, centralized, and 
aristocratic Military Services of Germany and Japan, 
intolerant of civilians and rigid with inter-Service 
jealousies, set up barriers to such a free flow. 

However, if our civilian-military collaboration was 
better than that of our enemies, it still left much to be 
desired. I fervently hope that men of goodwill in the 
Armed Services and in the Nation will discover how 
to make it what it should be—a close-knit partnership. 

For five years we in Division 12 collaborated with 
the Armed Services of the United States, Great Bri¬ 
tain, and Canada, the larger industrials, our col¬ 
leagues in the Office of Scientific Research and De¬ 
velopment, and our opposite numbers in Canada, 
Great Britain, and India. It seems doubtful that the 
experience we gained while pulling in this team dif¬ 
fers essentially from that of other divisions of the 
National Defense Research Committee. Yet we be¬ 
lieve that those who are now planning the basis for 
more effective future collaboration are entitled to our 
evaluation of the record for whatever it may be worth 
as the testimony of one small group, perhaps the 
smallest, in NDRC. 

From the lessons we learned—or relearned—in Divi¬ 
sion 12, we have drawn certain conclusions, of which 
we consider the following four the most important: 

1. We believe that the greatest possible decentrali¬ 
zation is vital to the successful functioning of a single 
research authority charged with coordinating the de¬ 
velopment of new weapons. We have seen what hap¬ 
pened in Germany and Japan with pyramidal, au¬ 
thoritarian organizations in charge of new weapons. 
We have also seen how effectively OSRD functioned. 
I am satisfied this was due largely to the farsighted 
policy of Dr. Bush, who carried decentralization to 
such an extent that we in Division 12, for example, 


were always able to use our autonomy to discover 
channels in which to explore possibilities and push 
ideas. It seems to me to be healthy that those with 
ideas should have more than one market in which to 
sell them, and that the Services, on the other hand, 
should be free to compete for such ideas. This is not 
a plea for the anarchy of indiscriminate channel¬ 
jumping or for secret Service rivalries, but rather a 
plea to preserve many channels within the frame¬ 
work of whatever Joint Command is finally adopted 
and to keep them open for navigation. 

2. I believe that in this war we closed too many 
channels to navigation and thereby overdid “secur¬ 
ity,” some of which was perhaps more fancied than 
real. It should be possible in the future to strike a 
nicer balance between measures designed to achieve 
true security and the speed-up that comes when col¬ 
leagues can talk with each other. It was perhaps for¬ 
tunate for our side that compartmentation was appar¬ 
ently carried to even greater extremes by our enemies. 

3. Admiral Mahan, speaking of the “unduly long” 
interval between changes in weapons and the result¬ 
ing changes in tactics, says: “This doubtless arises 
from the fact that an improvement of weapons is due 
to the energy of one or two men, while changes in 
tactics have to overcome the inertia of a conservative 
class; but it is a great evil.” I feel strongly that the way 
to overcome this evil in the shortest time is to recog¬ 
nize that those who develop a new weapon have a 
responsibility for supervising its early appearances in 
combat, until its full tactical exploitation becomes 
thoroughly well understood by all ranks. I could cite 
many examples. Two from my own experience are 
the DUKW and the antiaircraft barrage south of 
London against the German V-l robot. In each case 
the civilian expert, working in combat and with Staff 
authority, doubled or trebled the tactical effective¬ 
ness of the weapon. Army forces in the field were 
cjuick to recognize the value of this type of civilian 
collaboration. 

4. To a great extent we were merely merchants of 
ideas, and, in the desperate hurly-burly of the crisis 
years, we forgot at first certain truisms about how to 
sell ideas. We relearned them the hard way. I recite 
them here, not as discoveries, but merely as a check 
list: 

a. Present an idea only after it has been thought 



VII 



viii 


FOREWORD 


through to a tactical application. Then present it in 
correct military language. 

b. When presenting an idea to a tired man already 
crushed with responsibility, do so in a way that makes 
a minimum of demand on his mental effort or imagi¬ 
nation. Present it visually, simply, and dramatically. 

c. Avoid discouragement over the inertia which 
must inevitably exist in every large military organiza¬ 
tion. Its members have many things to do and cannot 
move in all directions at once, not even in yours. 

d. Remember that it is unrealistic to expect some¬ 
body else to equal your enthusiasms about your idea. 

Division 12 was small, my technical staff consisting 
of two, later three, men; yet we were designated a 
“catchall” division. This directive, coupled with the 
strong inclinations of my associates, led us to develop 
in many unexpected directions to meet unforeseen 
contingencies. 

The rather varied activities which ensued were of 
two kinds. On the one hand, we were assigned specific 
projects. On the other, we were often asked for, and 
frequently we volunteered, suggestions in fields in 
which we could not ourselves operate to advantage. 
In these cases, we gave every possible impetus to the 
initial momentum of the project, but left it to other 
organizations, whether in NDRC or in the Services, 
to see the thing through. While it is not possible to 
assess such work throughout all of its ramifications, I 
think it is of some interest to list a few examples of a 
type of informal activity to which we devoted a good 
proportion of our total effort. 

Among such examples, I recall that in 1940 and 
1941 we made suggestions to Army Ordnance which 
resulted in the eventual testing of cast and welded 
tank frames and hulls and in a marked modification 
of the silhouette of American tanks. Related ideas, by 
themselves or with concurrent proposals from others, 
led eventually to the General Pershing tank. Other 
suggestions, such as a mechanism at the driver’s seat 
for controllably altering the width of tank treads, re¬ 
main to be tried out. At about this time, we joined in 
the chorus calling for more mobile heavy artillery, for 
higher velocity antitank weapons, and for the de¬ 
velopment of a dual-purpose antiaircraft-antitank 
mount. These suggestions involved projects which 
clearly could be handled to better advantage directly 
by Ordnance, and many of them were developed in 
time to be of use. One suggestion in late 1940 for an 
illumination defense against night bombing was later 
reported used by the Germans at Hamburg. Some in¬ 


teresting suggestions in 1941, in the field of infrared, 
were ultimately assigned to Division 16 of NDRC. In 
1941 we sketched up and proposed landing craft of 
the LST(l) type to transport amphibious medium 
tanks and launch them at sea. The LST idea, rejected 
at the time, was later carried out on the insistence of 
others. We were able to give some assistance to the 
second of these two projects, and amphibious tanks 
were effectively used at Okinawa in 1945. 

In December of 1941 we renewed an earlier sugges¬ 
tion for very long-range guided missiles as a means to 
sink the Japanese Fleet with airborne torpedoes. The 
agitation surrounding this project, known as Setting 
Sun, played a part in the creation of that Joint New 
Weapons Subcommittee of the Joint Chiefs of Staff 
which reviewed guided missile programs in 1942. 
This ultimately resulted in the creation of Divi¬ 
sion 5. 

In August of 1943, following meetings at the 
Quebec Conference, we were invited by CINCPAC 
to confer at Pearl Harbor on the problem of the 
amphibious assault. We proposed the powerful, elas¬ 
tic, and economical type of amphibious assault de¬ 
scribed in Chapter 4. Regrettably it was not adopted 
in time for Tarawa, but later we had the opportunity 
to display this type of assault in the Southwest Pacific, 
where it was adopted, eventually becoming standard 
operating procedure throughout the Pacific Theaters. 

In the course of our more formal activities, we were 
assigned some 34 projects which comprised about 100 
sub-projects. This work resulted in war production 
totalling about $300,000,000, at a cost for develop¬ 
ment of about $3,000,000 (1.0 per cent) and for super¬ 
vision of about $200,000 (0.07 per cent). When I re¬ 
call the pace at which these projects were driven, I 
feel that these ratios reflect the effectiveness of the 
planning with which my staff guided those furious 
activities. 

It will be for others to make an objective assessment 
of our contribution. In my opinion, those projects de¬ 
veloped under the cognizance of Division 12 which 
have had the most significant effect on the strategy 
and tactics of war are: 

1. The DUKW. 

2. The doctrine of the amphibious assault. 

3. The training programs for amphibious warfare. 

4. The amphibious tanks. 

5. The Weasel. 

6. The improvement of aircraft landing wheel 
brakes. 


" TTT N FTBl^N-PfA f? 




FOREWORD 


ix 


7. The development of automatic thread gages. 

8. The magnetic compass for tanks. 

While some of our projects involved a certain 
amount of original research, most of our design deci¬ 
sions, particularly as regards vehicles to cross soft ter¬ 
rain, were based on meager fundamental data which 
could not be amplified at the time. Although these 
vehicles were successful, we feel that basic research in 
this field would now lead to improved designs. 

We were recently asked by General Stillwell to sug¬ 
gest improvements in amphibious vehicles. We have 
outlined a program (Chapter 10) in which the most 
productive single item is this: While the potentiality 
of existing designs could perhaps be increased by half 
by refinements in the design, a still greater gain could 
be achieved by proper use of existing equipment. For 
example, in my opinion, adequate training and in¬ 
doctrination would have doubled the tactical use fac¬ 
tor of the DUKW fleet. 

My very great personal gratitude is due to Palmer 
Cosslett Putnam, who served as my executive officer 
from 1941 until August 1943; Roger S. Warner, Jr., 


who served as technical aide from 1942 and as execu¬ 
tive officer from August 1943 to December 1944; 
S. Murray Jones, who served as technical aide; James 
A. Britton, who served as administrative aide; and 
[. R. Kansas, who served as fiscal aide; and to William 
F. Durand, who served as Chief of Section 12.1. In 
addition, I am deeply obligated to the contractors 
and members of their staffs who worked closely with 
us, and to those other divisions of NDRC who pro¬ 
vided us generously with their advice, assistance, and 
even the services of their members and their facilities. 

We are indebted to the Members, and especially to 
the Chairman, of the National Defense Research 
Committee for wise guidance and financial support 
for our projects. In particular we are indebted to Dr. 
Vannevar Bush, who encouraged and supported our 
ideas, showed us the way out of our difficulties, gave 
us the freedom to do our job in our own way, and who 
always stimulated us. It has been an immense satis¬ 
faction to have earned his confidence. 

Hartley Rowe 
Chief, Division 12 






This volume, like the seventy others of the Sum¬ 
mary Technical Report of NDRC, has been writ¬ 
ten, edited, and printed under great pressure. 
Inevitably there are errors which have slipped past 
Division readers and proofreaders. There may be 
errors of fact not known at time of printing. The 
author has not been able to follow through his 
writing to the final page proof. 

Please report errors to: 

JOINT RESEARCH AND DEVELOPMENT BOARD 
PROGRAMS DIVISION (STR ERRATA) 

WASHINGTON 25, D. C. 

A master errata sheet will be compiled from these 
reports and sent to recipients of the volume. Your 
help will make this book more useful to other 
readers and will be of great value in preparing any 
revisions. 


CONTENTS 


CHAPTER PAGE 

1 The Work of Division 12 1 

2 Amphibious Jeep. 6 

3 The DUKW: Its Development 11 

4 The DUKW: Its Applications 65 

5 The Weasel.115 

6 Amphibious Gun Motor Carriage.151 

7 Paddy Vehicle.155 

8 Proposed Amphibious Vehicles.158 

9 Amphibious Devices.165 

10 Amphibious Studies.172 

11 Ponton Bridge Reactions 198 

12 Bridge, Ponton, and Ferry Designs.213 

13 Tests of Bridge Components 233 

14 Torpedo Protection for Merchant Vessels 239 

15 Land Combat Vehicles 253 

16 Land Vehicle Components 267 

17 Land Vehicle Studies 278 

18 Special Devices.287 

19 Special Studies .314 

20 Special Projects.332 

Glossary.337 

Bibliography 341 

OSRD Appointees 354 

Contract Numbers 355 

Service Project Numbers 358 

Index.359 



















Chapter 1 

THE WORK OF DIVISION 12 


11 ORGANIZATION OF THE DIVISION 

n July 1, 1940, a few days after the National De¬ 
fense Research Committee [NDRC] had been 
established by order of the President of the United 
States, the predecessor of Division 12 appeared under 
the title of Section C. This group was to conduct in¬ 
vestigations in the broad fields of subsurface warfare, 
electricity, mechanics, and transportation. Later, after 
several reorganizations, Division 12 was created and 
assigned the broad field of transportation. 3 

Sometimes by request but often on its own initia¬ 
tive, the division occasionally moved in other areas. 
As indicated in the Foreword to this volume, these 
extradivisional activities brought Division 12 person¬ 
nel into many varied fields not contemplated in their 
original assignment. 

Much of the time of division personnel was devoted 
to these extradivisional activities, and, while it is 
clearly impossible to assess their importance, it is be¬ 
lieved that these indirect contributions had a sub¬ 
stantial significance. 

Within its assigned area, the division was at first re¬ 
quested by the Armed Services to work principally on 
vehicle components. Later it was asked to develop 
whole vehicles, such as the amphibious jeep and the 
Weasel. It then became evident that one of the divi¬ 
sion’s products, the DUKW, had fallen into an un¬ 
fortunate position—approved by the High Command 
but unwanted, unused, or unappreciated by many 
Service units. The personnel of the division were 
therefore invited into war theaters to consult with the 
staffs of theater commanders on amphibious logistics 
and on the tactics of the amphibious assault. 

The division had hoped that it could begin de¬ 
mobilizing in April 1943 in order to free its personnel 
for these consultations in the theaters. The assign¬ 
ment of other responsibilities, however, made it im¬ 
possible for the division to terminate its operations 
until June 1945. 

During the periods of most intense operations, the 
technical staff of the division consisted of three men, 
with an administrative aide, a fiscal aide, and four 
office assistants in the Boston headquarters. Field 

a See OSRD Appointees, Contractors, and Service Projects, at 
back of volume. 


offices were maintained for a few months in New York 
and Washington. Because of the nature of the divi¬ 
sion and the projects it supervised, the technical staff 
was actually a field staff and members operated almost 
entirely in the field, either in this country or overseas, 
as their assignments required. 

At a time when the division was contemplating 
Project Turtle (the NDRC Tank), a number of dis¬ 
tinguished people were prevailed upon to accept 
membership in the division. The project was can¬ 
celled, however, and it never became necessary to call 
them into consultation. 

SUMMARY OF OPERATIONS 

121 Amphibious Jeep 

In the first major technical program undertaken by 
Division 12, the jeep was converted into an amphib¬ 
ian. The conversion consisted of wrapping a water¬ 
tight hull under the parent vehicle, adding a propel¬ 
ler and a rudder, and making other changes required 
for amphibious operation. After limited but success¬ 
ful field tests on pilot models, the new vehicle passed 
out of NDRC supervision and production. It suffered 
from inadequate testing, inspection, and supervision 
of production; failure to recognize the necessity for a 
continuing development program in closest liaison 
with the using Services; failure to recognize the neces¬ 
sity for special training; and inadequate preliminary 
consultations with the using Services. 15 

122 The DUKW 

In the spring of 1942, without Service approval, 
work was begun on the development of a wheeled 
amphibian designed to discharge military stores at a 
high rate of speed direct from ship to dump and to 
support amphibious assaults. The amphibian was 
soon named the DUKW. It was decided that it would 
be a conversion of the Army truck then in highest 
production, the General Motors 2i/2-ton, 6x6 truck. 

In June 1942, the War Department initiated a pro- 

b See Chapter 2 in this volume. 



1 




THE WORK OF DIVISION 12 


duction order for 2,000 units, but there was appar¬ 
ently no general Service acceptance of the vehicle. 0 

Under ordinary circumstances, the major work of 
the Olfice of Scientific Research and Development 
[OSRD] and its subdivisions on this program would 
have been terminated at about this point. In the end, 
however, these engineering phases came to represent 
only a minor and preliminary part of the OSRD con¬ 
tribution to the over-all DUKW problem. Accord¬ 
ingly, full-scale demonstrations were staged, special 
driving procedures were perfected, pressure was main¬ 
tained on continuing testing and modifications, and 
special logistical and tactical techniques and equip¬ 
ment were developed. These and similar activities, 
culminating in the use of the DUKW' in the invasion 
of Sicily in the summer of 1913, apparently satisfied 
the High Command of the potential value of the 
DUKW, but the Armed Services did not feel it advis¬ 
able to allow OSRD to withdraw from the project at 
this point. 

To realize the expectations of the High Command, 
it was found necessary that OSRD, in a second depar¬ 
ture from a strictly engineering assignment, accept 
requests to stage demonstrations in nearly every com¬ 
bat theater, initiate and supervise training and re¬ 
training programs, exert all possible pressure to ex¬ 
pedite modifications found essential in the field (and 
to make field improvisations in many cases), establish 
maintenance and operational procedures, assist in 
indoctrinating staff officers of many theater com¬ 
manders, and, finally, urge at theater-staff level the 
full exploitation of the DUKW not only as a logisti¬ 
cal but also as a tactical weapon of war. 

In descending order of importance, the principal 
shortcomings of the DUKW were its small size, the 
difficulty of unloading it, its poor performance in 
mud, and its low speed in water. To overcome these 
handicaps to both logistical and tactical performance, 
it is recommended that the DUKW be supplemented 
but not replaced by a 15-ton, 3^-track amphibian. 
The larger amphibian should be developed in two 
models, one for combat and one for support/ 1 

12 3 The Weasel 

The Weasel, a light, track-laying cargo carrier, was 
developed as a snow vehicle for a winter invasion of 

c See Chapter 3 in this volume. 

<i See Chapter -t in this volume. 


Norway. Later, it was modified for use in mud, sand, 
swamps, rice paddies, and similar difficult terrain. 
The first model, the T-15 or M-28, went into only 
limited production. The second model, the T-24 or 
M-29, went into full production and was used in both 
the European and Pacific Theaters where snow, mud, 
swamps, or marshes immobilized other vehicles. Al¬ 
though these first two models could float, they were 
not true amphibians, since they had no propulsive 
power in water. The third model, the M-29C, was de¬ 
veloped and put into production as a true amphibian, 
capable of operation not only in difficult land terrain, 
but also in deep water. The M-29C is equipped with 
special cells to provide added buoyancy, and with 
rudders, skirts, and other shrouding devices to permit 
water propulsion by means of its own tracks. e 

12 4 Amphibious Gun Motor Carriage 

Two other amphibian conversions were nearing 
completion at the end of World War II. One is an 
amphibious gun motor carriage based on the stand¬ 
ard M-18 gun carriage as designed and developed for 
use in land operations. It is self-propelled, using its 
own tracks for water propulsion, and can fire either 
ashore or afloat. A pilot model was undergoing final 
field tests at the end of the war. f 

, - 2-5 Paddy Vehicle 

The second is a paddy vehicle, a light, amphibious 
cargo carrier designed for use in rice paddies and 
similar water-covered areas. Based on the T-39 light 
tractor, a pilot model of this vehicle was constructed 
and was also undergoing final field tests at the end of 
the war.® 

L2 - 6 Proposed Amphibious Vehicles 

Several proposed amphibious vehicles were studied, 
but only one of these devices was carried as far as con¬ 
struction of a full-size pilot model. In a search for a 
large, amphibious cargo carrier, to be known as the 
Pelican, a survey was made of existing land vehicles 
and components available for use in large wheeled 
and half-track amphibians with rated payloads of 6 
tons or more. Designs were developed for a still larger 

0 See Chapter 5 in this volume. 

f See Chapter 6 in this volume. 

s See Chapter 7 in this volume. 





SUMMARY OF OPERATIONS 


3 


vehicle and plans were completed ancl model tests 
undertaken on a 15-ton, 3 / 4 -track amphibian. Several 
amphibious trailers were designed for use with the 
DUKW and one experimental unit was constructed. 
Tests indicated that this unit was not satisfactory for 
practical use. h 

121 Amphibious Devices 

Several types of flotation devices were designed and 
studied for converting tanks and other land vehicles 
into amphibians. Two of these devices were actually 
constructed—one in which pontons were placed fore 
and aft of a light tank and a skirt placed around the 
tracks, another in which pontons were placed fore 
and aft on both sides of a medium tank. The latter 
device was used on a small scale in the last amphib¬ 
ious assault in the Pacific. An improved amphibious 
trailer hitch and a special amphibious boic attach¬ 
ment were both completed and submitted to final 
field tests just before the end of the war. * i * 1 

128 Amphibious Studies 

Several fundamental studies and a general theo¬ 
retical consideration of design factors were other con¬ 
tributions in this field of amphibious research. One 
of these studies concerned track propulsion in the 
LJ'T cargo carrier and consisted of experimental tow¬ 
ing tank tests conducted on two different models of 
the LVT cargo carrier, one with tracks completely 
submerged and the other with the return tracks out 
of water. The test data showed that, under the condi¬ 
tions of the investigation a nd with the trac k used, the 
^e merged t r ac k is super ior, A more complete study was 
then conducted on the problem of submerged track 
propulsion. Although it was found that in no case can 
the efficiency of the track propulsion equal that of 
screw-propeller propulsion, proper design can greatly 
increase the efficiency of the former. Preliminary de¬ 
signs were made and theoretical studies were con¬ 
ducted on an amphibious structure to be used in an 
assault across mud. A survey of the fundamentals of 
amphibious design indicated the relative merits of 
the two types of design—the “ground-up” method, in 
which a completely new vehicle is conceived, and the 

h See Chapter 8 in this volume. 

i See Chapter 9 in this volume. 

j See Chapter 10 in this volume. 


“conversion” method, in which a mature, successful 
land vehicle is modified for use both on land and in 
water.-* 

1-2,9 Bridges, Pontons, and Ferries 

An extended investigation of ponton bridge reac¬ 
tions for structures typical of those used in military 
operations resulted in the development of simple 
methods for the analysis of both continuous, unartic¬ 
ulated bridges and articulated bridges. A basic analy¬ 
sis was made of both types. k A variety of bridge, pon¬ 
ton, and ferry designs was prepared for military use. 
Among them are a 20-ton articulated bridge, a port¬ 
able ponton bridge and ferry for 30-ton tanks, a struc¬ 
ture designed for use as a ponton bridge or as a trestle 
or overpass for 60-ton tanks, a bridge constructed 
largely of steel pipe, a 200-foot portable bridge to 
carry a 30-ton tank, temporary highway trestles, a 
ponton ferry to support a 90-ton tank, tank-ferrying 
barges, an amphibious paddle-wheel towboat, a tank- 
transport vessel, several types of ramps, a landing 
pier, and several types of quays. 1 Standard laboratory 
tests of bridge components were performed on several 
types of wood, aluminum, and steel balk fasteners, 
and bolts used, or contemplated for use, in military 
bridges. 1 " 

1-2-10 Torpedo Protection for Merchant 
Vessels 

To provide improved safeguards against submar¬ 
ine attack, two types of wire nets were developed as 
torpedo protection for merchant vessels and were de¬ 
signed to be carried by vessels under way. One was 
found able to catch 30- to 35-knot torpedoes by their 
tails. The other, which can either be carried by the 
ships or be placed around them while moored, is able 
to stop 45- to 50-knot torpedoes by their heads. Both 
types were designed to give maximum efficiency, max¬ 
imum useful life, and minimum drag through the 
water. Electrically energized cables were developed 
for use with these nets as a protection against mag¬ 
netic torpedoes. The improved nets were not placed 
in production although various laboratory and field 
tests indicate their superiority." 

k See Chapter 11 in this volume. 

1 See Chapter 12 in this volume. 

m See Chapter 13 in this volume. 

n See Chapter 14 in this volume. 














4 


THE WORK OF DIVISION 12 


1211 Land Combat Vehicles 

Plans were made for the development of a new 
series of land combat vehicles designed to combine 
the best features of tanks already tested in battle with 
the best new features which could be developed. The 
new Turtle series included lightly armored but highly 
mobile units suitable for air transport, medium units, 
and heavy units. Mock-ups were prepared of repre¬ 
sentative types of the first two groups in the series. 
More detailed study was conducted on the light, 
highly mobile combat vehicle, which was developed 
to include all-wheel drive, a hydraulic anti-recoil sys¬ 
tem, and a new type of independent all-wheel suspen¬ 
sion enabling the vehicle to jump over ditches, fences, 
and similar obstacles. No complete full-scale vehicles 
were constructed. 0 

1,212 Land Vehicle Components 

As part of the general study on tanks but also as a 
development leading to an attempted improvement 
of existing vehicles, other investigations were con¬ 
ducted on tank components. A centrifugal, self-clean¬ 
ing air cleaner was devised for use in desert warfare 
but was found to be no better than available types. 
Mock-ups were made of various types of vision de¬ 
vices for tanks, protectoscopes, gun-shields, and other 
tank accessories. None of these devices was approved 
for production. In conjunction with another division 
of NDRC, a mobile rocket launcher was developed 
and placed in production for use on the DUKW.p 

1,2,13 Land Vehicle Studies 

In an effort to achieve reduction of tank noise, rec¬ 
ommendations were prepared which indicated that 
the noise of the M-3 light tank could be reduced to 
approximately one-third its usual level. Tests indi¬ 
cated that this could be accomplished in part by 
acoustical treatment of the crew compartment, the 
engine compartment, and the air intakes and outlets, 
and by the use of the most quiet types of tracks, but 
largely by the application of an adequate muffler and 
the installation of suitable rings or blocks to absorb 
the shock of the impact of the track blocks on the 
sprocket teeth. No practical use was made of these 
findings. A brief study of the reduction of bouncing 


in towed gun carriages led to proposed changes in the 
gun carriage suspensions and tow connections, but 
these were not accepted for use. q 

1,2,14 Special Devices 

Numerous devices and materials were likewise in¬ 
vestigated by the division as part of its catchall as¬ 
signment. These included primarily a study of air¬ 
craft landing wheel brakes and the development of 
improved designs achieving a threefold increase in 
capacity of energy absorption. These new designs 
made it possible for manufacturers to meet the speci¬ 
fications for such heavy bombers as the B-17, the B-24, 
and the B-29. Two new designs were prepared as sug¬ 
gested improvements on the Mark 51, Mod. 7 Navy 
bomb rack. Though both appeared to offer some ad¬ 
vantages in preliminary trials, neither was accepted 
for production. A new type of automatic thread gage 
was developed and put in production; in service tests 
these gages gave up to a 10-fold increase in speed and 
a 300-fold increase in life, making it possible to speed 
thread gaging in industry and to eliminate a serious 
bottleneck in the production of needed war materials. 
Of the thousands of pneumatic tire substitutes pro¬ 
posed for civilian and military service, the twelve 
most promising were constructed and tested; although 
none of these had been found satisfactory when the 
project was terminated, one of them had been run for 
more than 10,000 miles over paved and unpaved 
roads at speeds up to 85 mph and appeared to deserve 
additional study. A pneumatic life raft designed to be 
carried by aircraft was developed and tested; it is be¬ 
lieved to represent a decided improvement over exist¬ 
ing models by providing maximum comfort for the 
crew, protection against sun and rain, camouflage 
protection against air attack, and small bulk in stow¬ 
age, and in its ability to be sailed by inexperienced 
personnel. Plans were also made for an airborne life¬ 
boat but no model was built. Antifogging compounds 
incorporating wetting agents as the active ingredients 
were developed and found effective in temporarily 
improving the quality of vision through windshields 
and other transparent surfaces. The use of desiccat¬ 
ing devices, however, was recommended to prevent 
the fogging of some optical instruments. A group of 
new rain-repellent coatings was developed to improve 
visibility through rain-covered windshields, and al- 

Q See Chapter 17 in this volume. 


o See Chapter 15 in this volume, 
p See Chapter 16 in this volume. 









SUMMARY OF OPERATIONS 


5 


though none of these films provides prolonged pro¬ 
tection, some are effective for periods up to 300 min¬ 
utes in conditions simulating moderate to heavy rain¬ 
fall. A sine-clisk propeller designed for use in shallow 
water even when fouled with heavy marine growths 
was found in tests to give only low speed and to suffer 
from considerable cavitation and vibration. An im¬ 
mersion heater operated from the storage battery to 
heat the oil in the reservoir and other modification 
devices were developed to facilitate the cold weather 
starting of tank engines after they had been exposed 
to temperatures as low as —40 C. r 

1215 Special Studies 

Ship turning research was conducted on numerous 
models and the results correlated with tactical data 
on full-size naval vessels in an attempt to determine 
and evaluate the effect of hull design and of hull ap¬ 
pendages on the maneuverability of destroyers and 
other ships. Recommendations were prepared for 
general design features which would improve ship 
turning. This work, together with cavitation research 
studies, was turned over to the Navy for continuation. 

In an attempt to correlate the performance of such 
vehicles as the Weasel on snoiu characterized by dif¬ 
ferent properties, it was found that vehicle perform¬ 
ance is affected by the density and depth of the snow, 
the penetration into the snow at different ground 
pressures, the water content of the snow, and particu¬ 
larly the shearing strength of the snow at different 
ground pressures. Correlation of these factors with 
meteorological conditions has shown that it is pos¬ 
sible to make satisfactory forecasts of vehicle perform- 

r See Chapter 18 in this volume. 


ance on snow not merely for a period of 12 to 24 
hours, but even for many days ahead. An attempt to 
reduce the visibility of ivakes of small amphibious 
vehicles used in land operations led to tests on chemi¬ 
cal mixtures and mechanical baffles proposed as wake 
suppressors. Under the conditions of the tests, none 
of the mixtures or devices was found to possess any 
practical value. In a program of wi?id and wave 
studies, measurements of wave height, wind velocity, 
wave speed, wave length, and the velocity of pro¬ 
pagation of waves, followed by the correlation of 
these measurements, made it possible to predict 
wave heights from wind velocities with reasonable 
accuracy. 8 

1,216 Special Projects 

In order to conduct attacks on Japanese fleet units 
and dams, plans were made for a 10 -ton, controllable 
missile to be delivered by means of B-17’s which 
would either be operated by a skeleton crew or be 
equipped with television and operated by remote 
control from a B-29 flying beyond range of enemy 
fire. Other special projects undertaken by the divi¬ 
sion or its antecedents include the magnetic compass 
for tanks, the odograph, land mine detectors, an 
ultrasilent motor generator, map reproduction de¬ 
vices, defense methods against night bombing, and 
plans for long-range, glider-borne aerial torpedoes to 
be towed and radio-controlled by heavy bombers. Per¬ 
sonnel of the division likewise cooperated in the de¬ 
velopment of devices and methods for navigation in 
landing operations and for the destruction of land 
obstacles, and in the Manhattan Project. 1 

s See Chapter 19 in this volume. 

t See Chapter 20 in this volume. 


‘ eO NFfD EN - TT A4r- 









Chapter 2 

AMPHIBIOUS JEEP 

(*4-Ton, 4x4 Amphibian Truck) 


Summary 

uring the autumn of 1941 the 1,4-ton, 4x4 general 
purpose truck was converted into an amphibian 
for use in carrying personnel. The chassis, power 
plant, transmission, differential, and wheel compon¬ 
ents of the parent vehicle were used in a hull with a 
propeller mounted in a tunnel, the necessary power 
take-off, a marine rudder interlocked with the wheel 
steering system, a bilge pump, a capstan, and other 
marine appurtenances. After limited held tests on 
pilot models, the new vehicle went into production 
with an original order of 6,000. Because of insufficient 
early testing of production models, inadequate in¬ 
spection and supervision of production, failure to 
provide for a continuing development program, fail¬ 
ure to recognize the necessity for training, and, par¬ 
ticularly, failure to consult the using Services before 
production began, the amphibious jeep a was later 
discarded as a technical and tactical failure. 

2- 1 THE PROBLEM 

The conversion of the well-tested and accepted 
l^-ton, 4x4 general purpose truck into an amphibian 
—the first major project undertaken by Division 12— 
was first suggested in the summer of 1940 by the 
Quartermaster Corps, which initiated a formal re¬ 
quest in the spring of 1941. This request included 
general specifications calling for a vehicle which, 
while retaining the land maneuverability of the jeep, 
would also be able to travel in calm or protected 
water at about 5 mph. 

22 PROCEDURE 

After a preliminary survey, it was recommended 
that the problem be solved by a full, permanent con¬ 
version of the standard 14 -ton, 4x4 vehicle. 1 * Other 

a Project OD-95, formerly QMC-4. 

b This investigation was conducted by Sparkman & Stephens, 
Inc., New York, N. Y., under OSRD contract OEMsr-154. 

c These tests were performed at the Stevens Institute, Hobo¬ 
ken, N. J. 


proposals, including the use of detachable pontons 
and glider wings, were rejected. A program of towing 
tests was conducted on scale models, 0 and then, at the 
suggestion of the War Department, a contract was 
placed with the Marmon-Herrington Company d and 
later a development contract was made with the Ford 
Motor Company.** Both companies were authorized 
to produce pilot models according to the specifica¬ 
tions already established on the basis of scale-model 
studies, and each followed relatively independent 
courses of development. 

A lightweight, welded hull was prepared to include 
the necessary tunnels for axles, drive shafts, and pro¬ 
peller, and necessary seals were incorporated. In the 
Ford models, the hull structure was so designed that 
the normal chassis frame of the nonamphibious jeep 
could be retained. The other major additions in¬ 
cluded a power-driven bilge pump with an output of 
approximately 50 gallons per minute, a power-driven 
capstan in the forward deck, the necessary drive for 
the propeller, and a marine rudder operated from the 
regular steering column. Shielded air intakes were in¬ 
stalled to supply air to the engine during operations 
in rough water. 

In the Marmon-Herrington models, the power 
plant, transmission, differential, and wheel compo¬ 
nents remained the same as those on the parent 
vehicle, while the body was a waterproofed hull of 
welded steel construction with a propeller mounted 
in a tunnel at the stern and driven from the transmis¬ 
sion through a power take-off. Other additions in¬ 
cluded a marine rudder interlocked with the wheel¬ 
steering system, a hand bilge pump, a hand capstan 
with 3,500 pounds direct pull, and shielded circula¬ 
tion for the conventional cooling system. 

Both the Ford and Marmon-Herrington pilot mod¬ 
els were completed and submitted for tests between 
February and April 1942. 

d This investigation was undertaken by the Marmon-Her¬ 
rington Company, Inc., Indianapolis, Ind., under OSRD con¬ 
tract OEMsr-182. 

e This investigation was undertaken by the Ford Motor Com¬ 
pany, Dearborn, Mich., under OSRD contract OEMsr-487. 



G 





RESULTS 


7 



Figure 1. (A) Side view of Marmon-Herrington amphibious jeep. (B) Rear view of Marmon-Herrington amphibious 
jeep, showing the tunnel flap (to aid in going astern in water) raised to show tunnel. 


*•* RESULTS 

The Marmon-Herrington pilot model 1 (Figure 1) 
has an over-all length of 1791/2 inches, a width of 64 
inches, a height of 6734 inches, a ground clearance of 
13 inches, a weight light of about 3,500 pounds, and a 
weight loaded of 4,300 pounds. Maximum speed is 
65 mph on land and 5.5 mph in water. Grade ability 
is 60 per cent. After limited tests, this model was re¬ 
jected by the Army. 


The Ford pilot models 2 (Figures 2, 3, and 4) have 
an over-all length of 179i4> inches, a width of 61 
inches, a height of 41 (4 inches, a ground clearance of 
9(4 inches, a weight light of about 3,150 pounds, and 
a weight loaded of 3,950 pounds. Maximum speed is 
65 mph on land and about 6 mph in water. Grade 
ability is 60 per cent. Field tests showed that these 
models could climb out of fairly steep and partly iced 
river banks, cross ploughed fields, knock down trees 



Figure 2. Side view of production model Ford amphibious jeep. 









8 


AMPHIBIOUS JEEP 



Figure 3. In water, final pilot model of Ford amphibious jeep achieves speed of about 6 mph. 


up to 4 inches in diameter, and operate in moderate 
surf (Figure 5). After viewing demonstrations and 
motion pictures of these tests, the Commanding Gen¬ 
eral, Army Service Forces, placed a production order 
for 6,000 units. (Later, this was increased to 12,774 
units.) At this point, Division 12, having carried out 
its instructions, felt that the future of the vehicle lay 
between the manufacturer and the Army, and conse¬ 
quently turned its attention to other problems. 

It soon became apparent that the amphibious jeep 
was not welcomed by the Army Ground Forces, who 
contended, first, that the vehicle was not seaworthy, 
second, that they had not been consulted during its 
development, and, third, that it filled no military 
need. It was not required as a scout car nor as a tacti¬ 
cal vehicle, and it was too small to possess value as a 
logistical vehicle. 

Many of the first thousand amphibious jeeps de¬ 
livered to the Army sank after a few hours or days of 
operation—which did not endear the vehicle to pre- 



Figure 4. Rear view of production model Ford amphib¬ 
ious jeep. 



viously lukewarm military customers. 

It has become apparent that underlying the failure 
of this vehicle were a number of causes for which the 
responsibility must be shared by Division 12, the 
Army, the designers, and the manufacturers. 

In the first place, Division 12 personnel, by the de¬ 
ceptive ease with which they handled the vehicle in 
surf, contributed materially to an over-optimism soon 
displayed by high-ranking officials of the Army Serv¬ 
ice Forces. However, the failure of the vehicle was not 
primarily due to its inability to negotiate surf. 

When the design was frozen for production, the 
manufacturer transferred his design engineer to a 
glider project. There was a discontinuity between de¬ 
sign and production. The new workers recruited for 
the assembly line were placed under supervisors new 
to the project. During the critical early period of pro¬ 
duction, there was no liaison between the design engi¬ 
neer and this new group or their supervisors, who 
were not familiar with the amphibious purposes of 
the vehicle nor with the significance of many assem¬ 
bly details. Division 12 had not yet learned the neces¬ 
sity for keeping in touch with the production of a new 
weapon and transferred its project engineer to the 
DUKW project. As a result of this failure, faults 
which became immediately apparent in early field 
use remained uncorrected, and vehicles continued to 
sink because of poor welding, erratic clearances, and 
a number of assembly practices which might have 
been satisfactory for a land vehicle but which, in the 
case of an amphibian, became sufficiently serious in 
the aggregate to result in grounding the vehicle in 
most commands. 

Division 12 failed to insist, in the face of reputed 
manufacturing difficulties, upon the functional speci¬ 
fication that the ignition system be waterproofed, as 


^ ONITDEN -Tk -ytr 





















RESULTS 


9 


was later carried out on the DUKW. When the feasi¬ 
bility of this was determined in the case of the 
DUKW, a suitable system of waterproofing the jeep 
ignition was immediately developed and later ap¬ 
proved by the Office of Chief of Ordnance, Detroit. 
Because of long delays in placing it in production, all 
but 420 vehicles were delivered without it. 

Division 12 had not yet learned the necessity for a 
logical and continuing development program. In the 
absence of such a program, design errors such as too 
small tires and excessive weight all remained uncor¬ 
rected even after their serious effects became appar¬ 
ent. At the time the final pilot model was accepted, it 
appeared that the weight light could be reduced from 
3,150 pounds to perhaps 3,000 or less, but instead 
more equipment was added so that the final weight 
reached nearly 3,500 pounds. Introduction of a 12- 
volt electrical system at the insistence of the Signal 
Corps indicated that little or no consideration had 
been given to the effect of this on weight nor to the 
even more serious problems of overloading the fan 
belt and interfering with engine cooling. Insufficient 
thought was given to balanced cooling during opera¬ 
tion in rough water with the forward intake closed. 
Throughout the development it had been assumed 
that this hatch would be closed for only a few min¬ 
utes, but in actual operations it was found that occa¬ 
sionally this hatch would have to remain closed for 
much longer periods. 

The early production models were not adequately 
field tested. Surf testing was not continued on produc¬ 
tion vehicles. Pilot model testing had been conducted 
without consideration of performance in mud or soft 
sand, and the only sand tests were those carried out on 
a relatively hard and flat area at Virginia Beach which 
did not reveal the difficulties which the amphibious 
jeep would face on less suitable sand. As a result, the 
need for larger tires and the desirability of providing 
means to change the tire pressure while under way 
were overlooked by Division 12. In cold-weather tests 
of the pilot models, the vehicles were always kept in a 
heated storage room and consequently were not seri¬ 
ously affected by ice forming in the hull and in the 
pump system—a situation which became quite serious 
in actual field operation. 

A further major factor in the failure of this vehicle 
was the failure of the Army to institute a training pro¬ 
gram. Later, after some 2,000 vehicles had been pro¬ 
duced, Division 12 and the manufacturer attempted 
jointly to introduce such a program to salvage the 


vehicle, but this proposal was turned down by the 
Army on the grounds that it would merely waste man¬ 
hours on a vehicle for which no essential role actually 
existed. The lack of a training program resulted in 
the failure of the drivers to get an adequate under¬ 
standing of the operation and the limitations of the 
vehicle. Adequate publications and other training 
matter needed for vehicle operators and maintenance 
men did not reach the field until many months after 
the vehicles had been delivered and had failed. 

Reports of these failures and the underlying causes 
for them reached Division 12 only by chance, and im¬ 
mediately every possible step was taken, in collabora¬ 
tion with the manufacturer and the designer, to im¬ 
prove the vehicles in the process of production, and 
to prepare modification kits and get them to motor 
pools and embarkation centers for the improvement 
of vehicles already delivered. Despite these efforts, it 
was impossible to catch even a substantial number of 
the vehicles before they reached their eventual users. 
The 12,354th amphibious jeep to come off the pro¬ 
duction line still did not have a waterproofed engine. 
After 12,774 units had been produced, the line was 
shut clown. 

Division 12 and other divisions of the National De¬ 
fense Research Committee, together with many of the 
military agencies involved, derived a considerable 
education from this unfortunate experience. In the 
case of Division 12, these lessons were applied most 
profitably in the development of the DUKW, which 
was closely followed by division personnel from con¬ 
ception of the vehicle through production to its tacti¬ 
cal use by virtually every DUKW company, until 
after the end of the war. 



Figure 5. In moderate surf, early pilot model of Ford 
amphibious jeep impressed military observers. Produc¬ 
tion models were not waterproofed, and the engines 
drowned out. 









The DUKW, the “truck that goes to sea,” developed as an amphibian for operation on land and water and for the zone 
between—surf and treacherous sand. 


10 










Chapter 3 

THE DUKW: ITS DEVELOPMENT 


Summary 

n the spring of 1942, without Service approval, 
work was begun on the development of a wheeled 
amphibian designed to discharge military stores at 
a high rate of speed directly from ship to dump and 
to support amphibious assaults. The amphibian was 
soon named the DUKW. 

It was decided that it would be a conversion of the 
Army truck then in highest production, the General 
Motors 2i/2-ton, 6x6 truck. Pilot models were built 
with all main truck chassis units retained in their 
conventional location and with a watertight hull 
wrapped under the frame. A rudder, a propeller, 
bilge pumps, and other marine appurtenances were 
added. Later a controllable, central tire-inflation 
system was perfected and incorporated to adapt the 
DUKW for operation over a wide variety of beach 
conditions. 

In early tests, the DUKW showed a speed of about 
6.5 mph in water and 45 mph on land and readily 
negotiated the moderate surf available. Later tests 
showed it could go through quite heavy surf. 

In June 1942, the War Department initiated a pro¬ 
duction order for 2,000 units, but there was ap¬ 
parently no general Service acceptance of the vehicle. 

Under ordinary circumstances, the major work of 
the Office of Scientific Research and Development 
[OSRD] on this program would have been termi¬ 
nated at about this point. In the end, however, these 
engineering phases came to represent a minor and 
preliminary part of the OSRD contribution to the 
over-all DUKW problem. Accordingly, full-scale 
demonstrations were staged in rough weather to 
illustrate the strategic and tactical worth of the new 
weapon. Special driving procedures were perfected 
for operation not merely across soft sand but also 
across coral. Pressure was maintained on continuing 
testing and modifications. Special logistical tech¬ 
niques and equipment were developed to enable the 
DUKW to discharge loaded vessels, to dump cargo 
quickly on land, and to ferry tanks, trucks, and air¬ 
planes. Special tactical techniques and equipment 
were developed for carrying and firing the 105-mm 
howdtzer, the 25-pounder, the 3-inch antitank rifle, 
and the 4.5-inch beach barrage rocket. 


These and similar activities, culminating in the 
use of the DUKW in the invasion of Sicily in the sum¬ 
mer of 1943, apparently satisfied the High Command 
of the potential value of the DUKW 7 , but the Armed 
Services did not feel it advisable to allow OSRD to 
withdraw from the project at this point. 

To realize the expectations of the High Com¬ 
mand, it was found necessary that OSRD, in a second 
departure from a strictly engineering assignment, ac¬ 
cept requests to stage demonstrations in nearly every 
combat theater, initiate and supervise training and 
retraining programs, exert all possible pressure to 
expedite modifications found essential in the field 
(and make field improvisations in many cases), estab¬ 
lish maintenance and operational procedures, assist 
in indoctrinating staff officers of many theater com¬ 
manders, and finally urge at theater-staff level the 
full exploitation of the DUKW not only as a logisti¬ 
cal but also as a tactical weapon of war. 

At the end of the war, about 13,000 United States 
Army and Marine Corps troops had been organized 
into about 76 activated DUKW companies of 50 
DUKWs each. About 75 per cent of these men had 
been trained or retrained under OSRD supervision 
either in this country or overseas. About 5,500 British 
troops had been organized into 12 DUKW companies 
of 120 DUKWs each, and, similarly, most of these 
forces had received OSRD indoctrination in Eng¬ 
land, Scotland, or India. Additional small consign¬ 
ments of DUKWs were issued to units of the U. S. 
Coast Guard, Signal Corps, and other groups, some 
of which received OSRD training. 

A total of 21,147 DUKWs had been produced by 
August 15, 1945, and more than 6,000 additional 
units were on order. 

In descending order of importance, the principal 
shortcomings of the DUKW were its small size, the 
difficulty of unloading it, its poor performance in 
mud, and its low speed in water. To overcome these 
handicaps to both logistical and tactical performance, 
it is recommended that the DUKW 7 be supplemented 
—but not replaced—by a 15-ton, ^j-track amphibian. 
The larger amphibian should be developed in two 
models, one for a combat role and one for the support 
of the assault and for purely supply functions. 



12 


THE DUKW: ITS DEVELOPMENT 


3 1 INTRODUCTION" 

In the spring of 1942, some of the existing shipping 
difficulties and the nature of some of the probable 
offensive actions to come had been under study by 
OSRD personnel 15 for some time. 

It was known that Lend-Lease ships in ports such 
as Basra sometimes waited several months to be dis¬ 
charged into sailing lighters. In ports such as Bristol, 
the facilities were modern but insufficient to cope 
with war tonnage, and ships waited their turn. It 
seemed clear that if such ships, while lying in the 
stream, could be at least partially discharged directly 
to railroad sidings or dumps at a high rate of speed, 
their turn-around would be speeded and the effec¬ 
tive tonnage of the Allied merchant fleet increased 
proportionately. 

Further, it seemed clear that the invasion of Eur¬ 
ope, at whatever point, and the reconquest of islands 
in the Pacific would both require new techniques in 
landing operations and new amphibious equipment, 
including vehicles, to make these operations possi¬ 
ble. 0 Except in rare instances, it was expected that 
there would be no harbors or piers ready for use by 
the invasion forces, certainly not after Allied bomb¬ 
ings and sabotage and enemy demolition. There 
would be few beaches where cargo could be passed 
directly from ship to truck. Instead, it was expected 
that landings would be made on open beaches, over 
reefs and sand bars, and that military cargo and pos¬ 
sibly combat vehicles must often be carried from a 
ship first over deep water, then perhaps over sand 
or coral and more deep water, and finally either up 
to a transfer point or else directly to the combat units 
waiting for the supplies. 

No vehicles then in production or under develop¬ 
ment could adequately fill such multipurpose as¬ 
signments. The Roebling Alligator, progenitor of 
the LVT series as redesigned for the U. S. Marine 

a For a discussion of the military use of the DUKW, modifica¬ 
tions, training, and recommendations for future development, 
see Chapter 4 in this volume. 

b The development of the DUKW and its later application 
in various theaters were carried out by four men working at 
different times under the auspices of different components of 
OSRD. Thus, the development of the amphibian was directed 
by Division 12 of the National Defense Research Committee 
[NDRC]. The amphibious warfare missions to theater com¬ 
manders were carried out by former personnel of Division 12 
and of one of its contractors, serving as personal representatives 
of the Director of OSRD. Subsequent work along these lines 
in the Pacific Theaters was done under the administrative care 


Corps by Food Machinery Corporation, Borg-Warner 
Corp., and others, appeared to approach this goal 
most closely, but this track-laying amphibian is prim¬ 
arily for combat use and excels in mud and swamps. 
Its use as an open-sea cargo carrier is limited by poor 
maneuverability at shipside, relatively poor perform¬ 
ance in heavy surf, low land speed, relatively high 
maintenance, and excessive damage to roads con¬ 
tinuously subjected to its grousers. 

Early in April 1942, without formal request or ap¬ 
proval from the War or the Navy Department, and 
indeed in the face of high-level opposition to what 
was labeled “just another special vehicle,” the Direc¬ 
tor of OSRD authorized Division 12 to begin work 
on one such vehicle, soon baptized the DUKW. To 
save time in development and to simplify field main¬ 
tenance, it was arbitrarily decided that it would not 
be a “ground-up” design but a conversion of the 
Army truck then in highest production, the General 
Motors CCKW-353 2i/ 2 -ton, 6x6 truck. 

The basic design having been roughed out, de¬ 
velopmental engineering and experimental shop 
work were begun on April 24, 1942, at the Pontiac, 
Michigan, plant of the General Motors Corporation 
Truck and Coach Division, whose extensive design, 
research, test, and shop facilities were mobilized be¬ 
hind this project at the suggestion of Chief, Motor 
Transport Division, Office of Quartermaster Gen¬ 
eral. Personnel of Sparkman & Stephens, Inc., were 
placed in charge of marine problems/ 1 

Under ordinary circumstances, the major work of 
OSRD on this program would have been terminated 
with the completion of designs and the construction, 
testing, and modification of pilot models. This, how¬ 
ever, became an unusual program, and in the end the 
engineering phases came to represent only a minor 
and preliminary part of the role which OSRD was 
asked to play in developing the over-all potentiality 
of the Allied DUKW fleet. 


of the Office of Field Services [OFS], and in the European The¬ 
ater, under the administrative care of OSRD, London Mission. 

For simplicity, work done under any of these arrangements 
will be referred to in Chapters 3 and 4 as work done by or for 
OSRD. 

c See design for proposed tank carrier ship, to provide sea¬ 
lift for amphibious tanks (Chapter 12, Section 12.16); and pro¬ 
posed nestable ponton ferry (Chapter 12, Section 12.14). 

d This investigation was conducted by Sparkman & Stephens, 
Inc., N. V., under OSRD contract OEMsr-154, and by the Gen¬ 
eral Motors Corporation, GMC Truck & Coach Division (form¬ 
erly Yellow Truck & Coach Mfg. Co.), Pontiac, Mich., under 
OSRD contract OEMsr-870. 








INTRODUCTION 


13 


Once the development program was well under 
way, the next part of the problem was to obtain ac¬ 
ceptance by the Armed Services. 6 This was not easy. 
The DUKW idea did not sell itself. This idea may be 
recapitulated and summarized as follows: 

Logistical Uses of the DUKW 

1. To discharge military stores at a high rate of 
speed directly from Liberty ships lying in the stream 
to rail sidings or dumps, in harbors without modern 
facilities, like Basra; or in harbors with congested 
facilities, like Bristol; or in harbors which had been 
put out of action by war, like Cherbourg. 

2. To discharge combat stores at a high rate of 
speed directly from combat-loaded vessels (AKAs, 
LSTs, etc.) to dumps, possibly across beaches storm- 
lashed or girded by outlying reefs or bars. 

3. To evacuate casualties directly from forward 
areas to hospital ships, delivering the wounded to the 
receiving station on the boat deck without the shock 
of the sometimes unavoidably rough handlings at 
the surf line and at shipside. 

It was found that, with the high-speed DUKW 
mooring system by which the DUKW is automatically 
located precisely under the cargo boom, a suitably 
loaded ship could be discharged into DUKWs at a 
continuous rate in excess of 20 tons per hatch per 
hour. In 1942 and 1943, this implied a great reduc¬ 
tion in ship turn-around time and meant that a fleet 
of a few thousand DUKWs could, in effect, have 
added several million tons to the Allied merchant 
fleet. 

Tactical Uses of the DUKW 

1. To transport 105-mm howitzers, ammunition, 
and combat troops directly from a ship to a forward 
battery position for fire in support of an amphibious 
assault. 

2. To provide close-supporting barrage fire, with 
4.5-inch beach barrage rockets, during the critical 
minutes just before and just after a landing. 

3. To transport combat stores at a high rate of 
speed directly to forward positions from combat- 
loaded ships (AKAs, LSTs, etc.). 

4. In general, to achieve strategic surprise by sup¬ 
porting an assault on such a coast and through such 

e The amphibious jeep had been put into production with¬ 
out consulting the customers, who, without indoctrination, were 
allotted so many per division—an important factor in the failure 
of this amphibian to win many friends. 


heavy surf that the enemy “knows we will not land 
there.” 

Advantages 

These logistical and tactical doctrines imply sever¬ 
al benefits: 

1. A means is provided of getting mobile artillery 
ashore in close support of the assault and prior to the 
arrival of LSTs. 

2. There would be freed for other duties a very 
considerable number of troops and special equip¬ 
ment otherwise tied up in beach parties, sometimes 
forming human chains in the surf to pass stores from 
landing boats to skid pallets and then to trucks. 

3. Except in rare cases, the burden of the assault 
phase would not be increased by a requirement for 
bulldozers, Summerfeld matting, and other aids to 
beach crossing. 

4. From the foregoing, it follows that a beachhead 
supplied by DUKWs could expand faster than one 
supplied by LCVPs, LCMs, or other landing boats 
of the same general size. 

However self-evident they may appear in 1945, 
in 1942 these doctrines were simply the untried pro¬ 
posals of certain OSRD personnel and carried no 
conviction to policy-making officers in the War De¬ 
partment. Only the Chief, Armored Force, was inter¬ 
ested in the DUKW. He was seeking a means to get 
tanks ashore over outlying reefs, and the DUKW 
offered a possible solution to his problem. A largely 
futile sales campaign was carried on throughout the 
summer of 1942 in the face of continuing opposition. 
While a small production order had been placed in 
June 1942 on the directive of the Commanding Gen¬ 
eral, Army Service Forces [ASF], it was feared that, 
without general and warm Service acceptance, the 
DUKW would suffer the fate of the amphibious jeep 
—be issued to untrained troops and be condemned as 
a failure. This actually did happen to a small group 
of DUKWs at Milne Bay in June 1943. 

Accordingly, OSRD deemed it essential to mount 
a full-scale and compelling demonstration of the 
DUKW. With the assistance and encouragement of 
certain officers, particularly Colonel R. R. Robins, 
Development Branch, ASF, and General Daniel 
Noce, Commanding General, Engineer Amphibian 
Command, such a demonstration was organized in 
October, mounted in November, and carried out at 
Provincetown, Massachusetts, early in December 
1942. It achieved a limited objective, and 25 DUKWs 


COhrFTHFNTTAL 






14 


THE DUKW: ITS DEVELOPMENT 


were forthwith ordered to each of four theaters by 
the Assistant Chief of Staff, War Department Gen¬ 
eral Staff [WDGS], G-3. 

This limited acceptance, under these circum¬ 
stances, of such a highly specialized vehicle as the 
DUKW resulted in a delay in the development of 
training programs and training aids, in the selection 
of training centers, and in the indoctrination of 
higher command. These all inevitably lagged behind 
production, then getting under way, as well as behind 
the needs of the theaters. T his situation would have 
been less acute had the DUKW been recognized 
originally as a tactical weapon, but it was first ac¬ 
cepted as a purely logistical vehicle and its destiny 
was accordingly placed in the hands of the Transpor¬ 
tation Corps [TC]. This corps, functioning at a rela¬ 
tively low and noncombat echelon, was unable to 
command adecpiate facilities or personnel for the 
job of fully exploiting the strategic possibilities of 
the DUKW. 

When it was learned that a consignment of 
DUKWs was being sent to North Africa, and that on 
arrival their trained crews and officers were virtually 
all transferred to other duties, it was feared that this 
meant disaster to the DUKW 7 program, and OSRD 
requested permission to send training personnel to 
North Africa. This was refused. OSRD then re- 
cjuested the manufacturer to send personnel to North 
Africa to help with this training problem, but the 
manufacturer, not unreasonably, felt that he had 
no responsibility for the manner in which the Army 
used the DUKWs. Unwilling to let the weapon go 
by defaidt, OSRD arranged with the Assistant Chief 
of Staff, WDGS, G-4 to send an emergency photo¬ 
graphic training manual to North Africa, and de¬ 
cided to make itself available to work more inti¬ 
mately with the Armed Services in matters relating 
to the use of the DUKW. In response to War Depart¬ 
ment requests, and in cooperation with various of¬ 
ficers, OSRD personnel therefore set out to attack 
the problems of selecting training centers, drawing 
up and conducting training courses, creating train¬ 
ing aids, drafting Tables of Organization and Tables 
of Equipment, writing and editing training and 
maintenance manuals, attempting to arrange for a 
flow of spare parts, and, finally, assisting in the 
preparation of a sound film for the Joint New 
Weapons Committee of the Joint Chiefs of Staff, 
which outlined some of the strategic global possi¬ 
bilities of a large fleet of DUKWs. 


In March 1943, the 451st Amphibian Truck Com¬ 
pany [ATC] arrived in Noumea. It had been trained 
at Fort Story. It was in fine fettle. In a test it dis¬ 
charged a Liberty ship in Noumea Harbor directly 
to a dump at a rate of 22 tons per hatch per hour, 
compared with the average rate in Noumea at that 
time of about 7 tons per hatch per hour with lighters. 
The test was reported to the War Department. 

This report broke the ice. It was followed in July, 
after the invasion of Sicily, by a message from the 
Supreme Allied Commander, Mediterranean The¬ 
ater, to the Chief of Staff: 

“Amphibious truck, two and one-half ton, com¬ 
monly called DUKW, has been invaluable. It greatly 
facilitates flow of supply over beaches and on one 
beach was used as assault craft. Mechanism should 
be kept secret as long as possible. We would be de¬ 
lighted to get some more of them.” 

Production was stepped up and plans were drawn 
for the DUKW to bear a heavy share of the burden 
of supporting some of the forthcoming operations. 
OSRD redoubled the pressure to correct faults in the 
DUKW. 

For a time OSRD believed this high-level accep¬ 
tance meant that all necessary steps would be taken 
to institute more rigorous training and, especially, 
the indoctrination of field commanders. It was soon 
apparent, however, that while the DUKW fleet had 
looked good to General Eisenhower in comparison 
with the landing boat-human chain alternative, it 
had in fact delivered less than 25 per cent of its po¬ 
tential. In reality, the measures requisite to a realiza¬ 
tion of the High Command’s expectations could not 
be taken by the Military, not many of whom had had 
experience in small boats and still fewer, in surfman- 
ship. 

At this point, it was realized that OSRD had no al¬ 
ternative but to accept invitations to see the DUKW 
through into combat. 

LIpon invitation, OSRD personnel consulted on 
amphibious problems with the staffs of the theater 
commanders, including Commander-in-Chief, Pacific 
Fleet [CINCPAC], Southwest Pacific [SOWESPAC], 
South Pacific [SOPAC], Southeast Asia Command 
[SEAC], Mediterranean Theater of Operations 
[MTO], and European Theater of Operations [ETO], 

At the request of the Chief, Combined Operations 
(British), OSRD personnel were sent to Scotland in 
May 1943 to train British DUKW drivers, makegood 
equipment deficiencies, and supervise loading for the 


A vr 






DESIGN PROCEDURE 


15 


Sicilian invasion. Later, at the request of the Cont- 
mander-in-Chief, SEAC, similar assistance was pro¬ 
vided in India before the amphibious assault on the 
Burma coast. Similar requests resulted in the assist¬ 
ance of OSR1) personnel in Wales in training 
DUKW drivers before the Normandy landings, and 
later in supervising a DUKW school at Waimanalo, 
Oahu. 

A doctrine of amphibious assault was first pro¬ 
posed by OSRI) at a series of conferences called by 
CINCPAC at Pearl Harbor in August 1943. Pre¬ 
sented as being suitable for use at Tarawa, it was 
rejected by Amphibious Forces, Pacific Fleet. This 
doctrine, which was demonstrated later at Milne 
Bay, New Guinea, involved the coordinated use of 
LSTs, DUKWs, and LVTs, with the DUKWs carry¬ 
ing rockets and 105’s during the assault phase. It was 
used at Arawe and later became largely standard op¬ 
erating procedure throughout the Pacific. 

In SOWESPAC, OSRD personnel corrected abuses 
in DUKW 7 fleet operation at Guadalcanal; deter¬ 
mined by reconnaissance and map study the possi¬ 
bility of using DUKWs on Munda, Rendova, lvo- 
lombangara, Vella Lavella, Empress Augusta Bay, 
and the Treasuries; analyzed ship-to-shore logistics 
of the New Guinea ports of Milne Bay, Oro Bay, 
Buna Bay, and Lae; determined by reconnaissance 
the feasibility of using DUKWs at Finschhafen; 
evolved quantitative doctrines and established per¬ 
formance yardsticks for DUKW companies; and ar¬ 
ranged and supervised numerous demonstrations. 

Many conferences were held in theaters, including 
th ree highly productive ones at the request of Allied 
Forces Headquarters [AFHQ], Algiers, in December 
1943, at which daily tonnage rates to be guaranteed 
to the planners of the invasion of Southern France 
were recommended and the prerequisite training, in¬ 
doctrination, maintenance, and spare parts procure¬ 
ment programs were outlined, together with the 
tactical doctrines developed in the Pacific. 

The major problem of the optimum utilization of 
the Allied DUKW fleet was not solved at War’s end, 
and OSRD was requested to maintain its stopgap 
role until after V-J Day, when an OSRD representa¬ 
tive, having served on the Staff of the Commanding 
General, Army Ports, Okinawa, was sent to advise 
on the operation of the DUKW fleet in Korea. 

Scope of This Summary Report 

It is impossible in this Summary Technical Report 


to assess the original objectives of OSRD, the design 
decisions, the later recommendations for design 
modification at the factory and in the field, the 
various solutions to the problems of maintenance, 
or the conclusions and recommendations 11 without 
some reference to the logistical and tactical assign¬ 
ments actually given to the DUKW in theaters of 
operation and to the role of OSRD in shaping such 
amphibious doctrines. Accordingly, the chapters de¬ 
voted to the DUKW 7 are not wholly confined to a 
recital of engineering matters, but also touch briefly 
on such related portions of the over-all problem of 
the optimum use of the Allied DUKW fleet as may 
be necessary for a clear assessment of the technical 
work of OSRD. These related matters will be found 
described more fully in the historical records of 
OSRD. 

3-2 THE DESIGN PROBLEM 

As indicated above, the technical development of 
the I)UKW r was based on the arbitrary decision that 
this vehicle would not be a “grouncl-up” design, but 
a conversion of the General Motors Corporation 
CCKW-353 2i/2-ton, 6x6 truck. 

The basic specifications called for a water speed 
of about 6 mph, minimum profile, minimum weight, 
and land performance equivalent to that of the pa¬ 
rent land vehicle. The conventional location of all 
main chassis units would be retained and a water¬ 
tight hull would be wrapped under the frame and 
below the engine, transmission, and transfer case, 
leaving the wheels, axles, springs, and drive shafts 
exposed. 

3 3 DESIGN PROCEDURE 

3.3.1 The Fundamental Decision 

It was expected at the outset that developing a 
new amphibian by the conversion of a well-proved 
land vehicle already in production would accelerate 
the whole program, making it possible to utilize 
many standard components and design features, 
while at the same time simplifying maintenance in 
the field, since maintenance techniques and many 
spare parts for the parent vehicle would already be 
available. 

It was recognized that this decision sacrificed the 
possibility of the better water performance which 
might be expected from a “ground-up” design. The 


C ON e HM^ir rrr^ 




16 


THE DUKW: ITS DEVELOPMENT 


evidence indicates that this was a fortunate decision: 
in a global war, spare parts procurement proved a 
constant nightmare. 

3 - 3 - 2 Basis of the Design 

The General Motors Corporation CCKW-353 
2p2-ton, 6x6 truck/ (Figure 1) had been in produc¬ 
tion for a year and a half, it had been well received 
in the field, spare parts were already available at 
depots, and its design seemed well-suited to amphibi¬ 
ous conversion. Its engine had been in production 
for 10 years, and some 500,000 were in use on buses 
and trucks. 

In order to change this truck into the amphibious 
DUKW,s it was apparent that the CCKW power 
plant, transmission, transfer case, drive shafts, axles, 
brake system, and related accessories could be used 
without serious change, while the cab and body parts, 
fenders, hood, engine cooling system, winch drive, 
steering gear and controls, some frame members, and 
bumpers would have to be removed. The major new 
additions would include a hull, which would have 
to be designed specifically for the job, together with 
such accessories as a propeller, a rudder, bilge pumps, 
hull drain valves, air ducts, cargo compartment, 

fC for “1941,” C for “conventional,” K for “front-wheel 
drive,” and W for “two rear driving axles” (GMC symbols). 

eD for “1942,” U for “utility,” K for "front-wheel drive,” 
and W for “two rear driving axles” (GMC symbols). 


cockpit, windshield, coamings, hatch covers, instru¬ 
ments, controls, a modified engine cooling system, 
and a modified winch drive. 

The selection of the CCKW meant that 85 per 
cent of the amphibian would already be a mature, 
“debugged” mechanism. A great effort was made to 
“debug” the remaining 15 per cent of the conversion 
in a very short time. 

3 - 3 - 3 Scale Model Study 

Scale model tests of many proposed hull designs 
were run intermittently throughout the period from 
April 1942 to July 1943. h These included resistance 
tests on experimental designs and on the first pilot 
models, a study of the effect of various changes pro¬ 
posed for the hull, and tests on the production design. 
In addition, self-propelled tests were conducted on 
a scale model of the production design in order to 
aid in determining the stability, propulsive coeffi¬ 
cients, and turning characteristics of the final vehicle. 

Figure 2 illustrates the design of the first of more 
than a dozen scale models which were studied, while 
Figure 3 indicates the design which was finally in¬ 
corporated in the actual production amphibian. 

Tests on the scale models indicated that the full- 

h These tests were conducted by the Stevens Institute of 
Technology, Hoboken, N. J., under supervision of Sparkman & 
Stephens, Inc., New York, N. Y. 



Figure 1. General Motors Corporation CCKW 214 -ton, 6x6 truck, parent vehicle of the DUKW. 

















DESIGN PROCEDURE 


17 


size amphibian with a displacement of 20,390 pounds 
would give a speed of roughly 5.9 mph at a propeller 
speed of 950 rpm, 6.1 at 1,000, and 6.3 at 1,050. At 
5.9 mph the resistance in effective horsepower would 
be 16, at 6.2 mph it would be 19.2, and at 6.5 mph 
it would be about 21. 

Comparative results emphasized the beneficial ef¬ 
fects of housing the wheels, differentials, and suspen¬ 
sion in tunnels. A scow-type bow appeared desirable 
at the speeds tested for reducing resistance, increas¬ 
ing stability, and improving surf ability without 
interfering with land operations. 

3.3.4 Development of the Design 

Hull 

The hull was originally designed on the basis of 
fundamental engineering theory and the results of 
the scale model tests. Many of the original features 
were arbitrarily selected. For example, maximum 


ground clearance was established by the standard 
location of the bottom of the transfer case. Consistent 
with the ground clearance selected, it was thought 
desirable to let the hull provide maximum screening 
for the wheels and axles. The shape of the bow and 
the stern was controlled largely by arbitrarily se¬ 
lected angles of approach and departure. The prin¬ 
cipal bow plate was made flat for simplicity of 
construction. The hull sides were rounded at the 
bow to provide more clearance in maneuvering, 
better visibility, and less water resistance. The ex¬ 
treme tip of the bow was somewhat snubbed to de¬ 
crease over-all length and provide more rugged con¬ 
struction. In the stern, all possible displacement was 
retained to reduce the tendency of the stern to settle 
and thus to obviate the need for increased freeboard, 
which would make cargo handling more difficult. 
The maximum allowable beam of 96 inches was se¬ 
lected to give maximum displacement without ex¬ 
cessive height for land operations. This was later 
expanded to 99 inches including rub rails. 





SECTION C-C 


I 


Lrru 

SECTION B-B 



Figure 2. Design of first scale model of DUKW, showing sections of rear tunnel. 


-caSiFa ro E mi? - 








































































































































18 


THE DUKW: ITS DEVELOPMENT 



FORWARD 




tOF TRUNK 




SECTION D-D 


FRONT VIEW 


l-'Kj vAj l/Kj 

SECTION E-E SECTION SECTION G-G SECTION SECTION 

F-F H-H K-K 

Figure 3. Design of final scale model of DUKW used for towing tests. 



Figure 4. Cab-over-engine pilot model of DUKW, under way in water test. 


















































































































DESIGN PROCEDURE 


19 



Figure 5. Cab-over-engine pilot model of DUKW, first full-scale unit constructed. 


Actual water tests showed the benefit of extending 
the length of the stern in order to furnish additional 
flotation where it was sorely needed and to relocate 
the propeller for higher speed. Cutting back the 
rear portion of the front wheel cutouts proved 
slightly advantageous, while more obvious improve¬ 
ment resulted from adding covers over the front 
cutouts, which significantly reduced the visible bow 
wave. Rear wheel house covers were added later to 
protect accessory tire-pressure control leads. 

In the first pilot model, the cab was placed over the 
engine to give maximum visibility for the driver and 
maximum cargo space (Figures 4 and 5). In all other 
pilot and production models, however, the cab was 
placed behind the engine. This made it possible to 
lengthen the bow deck and cover the engine com¬ 
pletely, providing increased protection against water 
and more accessibility to the engine. With the cargo 
space thus moved back, the load on the front axle 
was relieved. By increasing the width of the com¬ 
partment, the necessary cargo space was maintained. 

Another revision resulted from a decision to econo¬ 
mize on steel by making the driver’s compartment 
out of plywood. 

Since the final hull design release in August 1942, 
the only important change in hull shape has been to 
raise the height of the cargo space coaming by 6 
inches at the rear end. This provides the added free¬ 
board to accommodate the increased loads which it 
was found practical to carry. In all hull construction, 
welded steel is used with liberal reinforcing (Figures 
6 and 7). 


Figure 6. Inside view of DUKW hull, showing construc¬ 
tion of wheel cutouts and tunnels for drive shafts. 



The hull is constructed of welded sheet steel, with 
a maximum plate thickness of about 0.1046 inch at 
the bow, 0.0938 inch at the bottom, and 0.0625 inch 
at the sides. Its relatively thin skin is reinforced in¬ 
side by transverse “hat section” channel frames and 
outside by similar longitudinal rub rails. The com- 
























20 


THE DUKW: ITS DEVELOPMENT 




Engine 

With the general specifications of the hull deter¬ 
mined, the next problem was to obtain the most effec¬ 
tive propulsive power. For efficiency in production 
and in field service, and because a larger engine 
would require a new power train, the standard CMC 
270 engine already used in the CCKW truck was 
adapted for the DUKW. This six-cylinder engine 
was satisfactory for land performance but required 
some modifications for use in an amphibious vehicle. 

In the first experimental model, with cab over en¬ 
gine, the limited space beneath the cab floor made 
it necessary to use updraft carburetion. In later pilot 
models and all production models, with the cab lo¬ 
cated behind the engine, standard downdraft carbu¬ 
retion was adopted. The muffler was altered to reduce 
the noise level, and the distributor, the coil, the 
spark plugs, the starter, and the generator were 
waterproofed. 

T he first pilot model had no provision for hand¬ 
cranking the engine at sea, thus leaving the vehicle 
completely helpless in case its mechanical starter 
failed. Production models were supplied with a spe¬ 
cially designed lever and ratchet on the water pro¬ 
peller shaft (Figure 8). 




plete hull is very stiff and requires no structural re¬ 
inforcement. 


Figure 8. Ratchet on water propeller shaft and special 
lever used for hand starting. 


Figure 7. Bottom view of 1944 production model DUKW, 
showing wheel cutouts and housings for drive shafts, and 
propeller tunnel. 











































DESIGN PROCEDURE 


21 



Figure 9. Power train of production DUKW. 



The power plant as used in the 1944 production 
models is shown in Figure 9. 

Propeller 

Once the power which could be expected from the 
engine had been established, major attention was 
given to the design of the propeller, its position, and 
the design of the propeller tunnel in the hull. 

Original estimates, which were supported by nu¬ 
merous tests, indicated that maximum efficiency 
would be given by a maximum propeller diameter 
and a pitch ratio of slightly more than 50 per cent. 
Although the maximum diameter was 26 inches, this 
was reduced to 25 inches to give needed additional 
ground clearance, and the pitch was set at 13i/> 
inches. These dimensions were used for the first pro¬ 
duction units, but the pitch was later changed to 14 
inches to give greater fuel economy. 

It was first thought necessary to run the engine at 
approximately 3,000 rpm in order to use the maxi¬ 
mum available power. In the course of the test pro¬ 
gram, however, it became apparent that virtually 
as good results could be obtained without exceeding 
2,500 rpm, since the power curve of the engine is 
comparatively flat in this range. It was therefore de¬ 
cided that the propeller should limit the engine to 
approximately 2,500 rpm at full throttle. This would 
permit the use of the standard governor, result in 
greater gasoline economy afloat, and increase the 
life expectancy of the engine. 

From the standpoint of marine propulsion, the 
largest practical propeller diameter was desirable. 
This was limited by ground clearance and space 
available for the tunnel and was finally set at 25 
inches. The most effective pitch for this diameter 
proved in theory to be between 13 and 14 inches; 
this was substantiated in the tests. It was found that 


the horsepower available at 2,500 rpm would turn 
this propeller at a maximum of approximately 1,100 
rpm, necessitating an over-all reduction from engine 
to propeller of approximately 2.3 to 1. 

The use of first speed in the transmission was the¬ 
oretically desirable. Coupled with the necessary over¬ 
drive in the propeller transfer case, this would give 
approximately the same maximum propeller rpm 
when reversing afloat, because of the fact that the 
transmission reduction would be about the same in 
first and reverse. Flowever, it was not practical to use 
first speed since the first speed gears had a limited life 
expectancy, and second speed was selected as the 
second choice. The propeller transfer case was de¬ 
signed with the necessary overdrive to convert the 
output of second speed to the maximum usable pro¬ 
peller speed (1,100 rpm). Since the transmission in 
reverse had about double the reduction of second 
speed, the maximum propeller rpm available for re¬ 
versing absorbed only about 50 per cent of the power 
used in driving ahead. 

After several months of field operations with pro¬ 
duction models, it was decided to substitute an inter¬ 
changeable, two-speed propeller transfer case, retain¬ 
ing the initial ratio for use with second speed for 
forward driving, and adding an overdrive of higher 
ratio, which provides approximately the same total 
reduction in reverse as in forward (Figures 10 and 
11). In steep landings demanding the use of first 
speed for wheel drive, this provides the additional 
advantage of enabling the propeller drive to be put 
in the overdrive position for maximum propeller 
thrust. 

The position of the propeller was determined as a 
compromise between moving it aft to increase effi¬ 
ciency and moving it forward to reduce its vulner¬ 
ability. 

















THE DUKVV: ITS DEVELOPMENT 


*><> 



Figure 10. Single-speed water propeller transfer case used 
in early models. 



Figure 11. Two-speed water propeller transfer case used 
in later production models. 


To simplify replacement and increase operating 
life, a replaceable journal with a sealed babbitt bear¬ 
ing was used in the outboard strut bearing of the 
propeller shaft and practically doubled operating 
life. A later development was a poured babbitt re¬ 
placeable journal with seals incorporated on each 
end to exclude water and retain grease; a sand 
slinger, split to facilitate removal, was added; and the 
strut mounting on the tunnel was strengthened by 
the use of larger bolts and pads. Operating life was 
thereby quadrupled. 

Some consideration was given to a retractable in¬ 
stallation in which the propeller would operate with 
its lower blade 18 inches below the profile of the 
stern. This position gave about 0.4 mph additional 
speed, but it was felt that this increase was insuffi¬ 
cient to justify the increased mechanical and opera¬ 
tional complications and the increased vulnerability 
which would result. 

Many modifications of propeller tunnel design 
were investigated to get the greatest propeller effi¬ 


ciency, vehicle speed, maneuverability, and ease in 
production. In the original design, the tunnel has 
vertical sides and sections resembling an inverted 
“U.” It later was found advantageous to open out the 
lower edges of the tunnel in front of the propeller, 
slightly decreasing protection to the propeller but 
increasing speed, and for more maneuverability it 
was found necessary to open up the tunnel behind 
the propeller (Figure 12). To avoid unnecessary die 
work in production, it was desirable to retain simple 
curvature, and in the final design only the center 
portion of the tunnel has compound curvature (Fig¬ 
ure 13). 

The top of the propeller tunnel was located as 
high as possible without raising its outlet above the 
water line when the vehicle is unloaded. Any in¬ 
crease above this level results in air reaching the 
propeller when the vehicle goes into reverse, seriously 
reducing the thrust. 

In an attempt to reduce the severe turbulence in 
the wake, the rear part of the tunnel top was sloped 












DESIGN PROCEDURE 


23 



Figure 12. Final revised tunnel shape, propeller position, 
and rudder post angle. 


downwards, but tests showed that while this altera¬ 
tion improves the appearance of the wake, it reduces 
the speed of the vehicle. 

Marine Steering 

In the propeller tunnel of the original pilot model, 
the lower corners were designed to give maximum 
protection to the propeller and the rudder. The 
rudder was placed on the propeller shaft center line, 
rigged to turn a maximum of 40 degrees on each side 
of the center line, and controlled by %-inch galva¬ 
nized cables connected to a steel spool on the truck 
steering column (Figure 14). 

Because of the large turning diameter, particularly 
when turning to the left, this design was changed by 
moving the rudder to the left of the center line, open¬ 
ing up the lower edges of the tunnel behind the 
center line of the propeller, and installing the rudder 
stock at an angle of 20 degrees forward and upward 
from vertical. Linkages (Figure 15) were introduced 
so that an equal number of wheel turns in either di¬ 
rection would have an equal effect in turning the 
vehicle. 

Although this modification resulted in a consider- 
able improvement, rudder response was slow and the 
rudder was found unbalanced, turning full right if 
the wheel were released. Later, an offset tab (Figure 
16) was fixed to the rudder, eliminating the inherent 
tendency to swing to the right, and a new linkage 
system was developed to provide rapid rudder action 
for small movements of the steering wheel (see Fig¬ 
ure 17). 



Figure 13. Bottom view of hull, showing final design of 
propeller tunnel. 


Bilge Pump System 

Early in the development of the DUKW, it was 
realized that because of the low freeboard desirable 
for satisfactory cargo handling, the probable use in 
surf, and the undesirability of cargo space covers, con¬ 
siderable quantities of water would be shipped dur¬ 
ing normal operations and consequently an efficient, 
high-capacity, foolproof bilge pumping system would 



Figure 14. Rudder cable spool on steering column. 


























24 


THE DUKYV: ITS DEVELOPMENT 




Figure 16. Revised rudder design with cutaway leading 
edge, rear tab, and sloping rudder post. 

pump for use when the propeller shaft is not turning 
or when the engine is stopped. 

The manifold pump, initially a belt-driven gear 
pump, unfortunately performed without failure 
throughout the pilot model tests but failed to stand 
up under field conditions. Because of the inherent 
vulnerability of this type of pump to sand and dirt, 
its need for very frequent lubrication, and the im¬ 
practicability of necessary fine-meshed, protective 
screens, it was soon replaced by a Gould “water pis¬ 
ton” pump. This latter device is not readily damaged 
by abrasion and can actually help clean out sand 
from the hull. Manual controls (Figure 18) enable 
the operator to use any or all of the intake lines. 

The centrifugal pump used on the first pilot model 
was driven through a double V-belt drive, which was 
impractical and inefficient since it slipped when wet. 
This pump was later used with a single chain drive, 
which lacked transverse stability, and finally with a 
double chain drive, which gave a satisfactory capac¬ 
ity of 225 gallons per minute (Figure 19). 

For the hand pump, a barge-type pump with a 
capacity of about 25 gallons per minute was origi¬ 
nally strapped on the forward deck so that it would 
be readily accessible. This location, however, proved 
to be too exposed to heavy boots, and the pumps were 
frequently found squashed flat and inoperative when 
needed. Furthermore, such a portable pump can 


Figure 15. Original production rudder-control arrange¬ 
ment with linkages introduced to equalize turning circles. 

be essential. It was also realized that unlike a boat, 
which operates exclusively in water, the 13UKW 
would spend much time on the shore, picking up not 
only cargo and personnel but also sand, dirt, and 
other foreign matter which would raise havoc with 
ordinary bilge pumps. 

Three bilge pumps were specified: (1) a self-prim¬ 
ing manifold pump, driven by the propeller shaft and 
used continuously to keep the separate bilge compart¬ 
ments dry; (2) a stand-by, high-capacity, centrifugal 
pump, also driven by the propeller shaft, which starts 
pumping when the water level in the center bilge gets 
deep enough to prime the pump; and (3) a hand 


Figure 17. Quick-action rudder-control arrangement used 
in later production models. 






















DESIGN PROCEDURE 


25 



Figure 18. Manual controls for bilge pump manifold. 

rarely reach bilge water in the stern when the DUKW 
is fully loaded. An improved, built-in hand pump 1 
was designed and recommended by OSRD in Novem¬ 
ber 1943 and was approved with some modifications 
in June 1945 but never got into production. 

It was recommended that all outlets for these 
pumps be visible to the operator so that he may know 
whether the pumps are working and whether the hull 
is leaking. 

Hinged screens for bilge discharge were installed 
later to prevent foreign matter from dropping into 
the discharge pipes, and a small conduit was added to 
direct warm air on the bilge pumps and selector mani¬ 
fold in order to prevent freezing in colcl-weather 
operations. 


i See Table 2 in Chapter 4. 



Figure 19. Gould pump with double chain drive. 


The final bilge pump system (Figure 20) has a total 
capacity of more than 300 gallons per minute- 
enough to cope with the water coming in through a 
3-inch hole in the hull. 

Hull Drain Valves 

Since drain valves or dump valves as used in mili¬ 
tary tanks had generally proved cjuite unsatisfactory, 
no such valves or sea cocks were installed in the origi¬ 
nal DUKWs. Instead, the bilge pump intakes were 
located close to the low points of the hull so that they 
would remove almost all of the water. This method, 
however, made the pump intakes too vulnerable to 
dirt in the bilge, and some water remained in the 
bilge at all times. Later, four drain valves were in¬ 
stalled with extension handles (Figure 21), one for¬ 
ward of the front axle, one behind the driver, and one 


/- A 



Figure 20. Bilge system in final production units, including three suction lines leading to pump under driver’s seat 
and one line leading to pump under cargo floor. 






















































26 


THE DUKW: ITS DEVELOPMENT 



Figure 21. Drain valve with extension handle(left),shown 
with bilge suction cup (right). 


in each bilge behind the rear wheel pockets. All 
handles can be reached without opening any hatches. 

Water Sealing 

Much study and testing were needed to devise 
means for keeping water out of submerged axle units 
and propeller shaft openings in the hull. Water oper¬ 
ations resulted in an unusual difficulty by chilling the 
air in the axle housing so suddenly that the resultant 
high vacuum would force water past conventional 
seals. To prevent this, vents were provided in the 
form of rubber hose leading into the hull. 

Double-lipped seals were installed on all pinion 
shafts, rear hubs, and pillow blocks. A major sealing 
operation was performed where the three drive shafts 
pass through the hull to the axles (Figure 22). The 
housings which enclose these shafts not only seal 
holes in the hull but also protect the shafts from ob¬ 
stacles and prevent entanglement with barbed wire 
and brush. These housings were modified several 
times to give increased clearances, stiffness, and ac¬ 
cessibility. 

A rubber sheeting was used first to seal the point at 
which the steering gear leaves the hull, with a double- 
lipped seal used on the shaft. A gasket with a clamp 
plate coated with sealer was used on later models. 

The rudder and water propeller shafts are sealed 
by conventional marine-type stuffing boxes. 

Some of the truck axle modifications originally 
ordered for the DUKW were later adopted for stand¬ 


ard CCKW trucks to enable them to survive the 
“wading” involved in amphibious warfare. 

Lubrication 

The corrosive action of salt water on exposed bear¬ 
ings makes it essential to provide for frequent Hush¬ 
ing and lubrication. Graphite bushings proved inade¬ 
quate on control shafts and levers, making it necessary 
to add grease-gun fittings. The pillow block, origi¬ 
nally an oil-filled housing, was improved by incorpo¬ 
ration of provisions for grease-gun lubrication. 

Engine Cooling 

The DUKW cooling system is unusual in that air 
is drawn from behind the driver’s compartment, 
pushed through the radiator, and exhausted through 
ducts on each side of the compartment (Figure 23). 

Some fifty different combinations of fans, radiators, 
shrouds, and ducts were tried during the develop¬ 
ment of this system. Beginning with the standard 
CCKW truck radiator and fan size, the outlet ducts 
were enlarged, the shrouds improved, the fan in¬ 
creased in diameter, a fairing added ahead of the 
radiator, and the radiator moved ahead and finally 
increased in size. Despite the added size of the fan and 
the reversed flow of air, the power absorbed by the 
fan is no greater than that absorbed in the CCKW 
truck—about 8 lip at 2,750 engine rpm. 

The fan, radiator core, and air passages were devel¬ 
oped to provide balanced cooling when operating 
afloat at the torque peak of the engine (1,200 rpm) at 
an ambient temperature of 115 F. It was found, how¬ 
ever, that cooling on land was between 5 and 10 de- 



Ficure 22. Housings for rear drive shafts. 













DESIGN PROCEDURE 


27 


grees less effective, and this was rectified by installing 
an auxiliary air intake scoop directly over the engine, 
to be opened, as necessary, during land operation only. 

Field operations indicated that the original inten¬ 
tion was disregarded and that the auxiliary air intake 
was frequently opened during water operation, the 
result either of driver forgetfulness or of the need for 
additional cooling which resulted from neglect of 
some other parts of the cooling system. Water inevi¬ 
tably came through the opened auxiliary air intake 
and tended to create serious maintenance problems 
in the engine and electrical system. Carburetors, gen¬ 
erators, exhaust manifolds, voltage regulators, and 
wiring all suffered. There were occasional accidents 
when the quantity of water would temporarily short 
out the engine. Consequently, production of the 
auxiliary air intake was discontinued at the end of 
the first year, additional specific instructions were 
issued to overcome temporarily unsatisfactory cool¬ 
ing, and cooling was improved by more complete seal¬ 
ing of the hot air outlet ducts, thereby reducing 
recirculation. 

Heating System 

Frequently large bodies of water will remain open 
in freezing temperatures, and an amphibian operat¬ 
ing under these conditions must be protected from 
water freezing in the bilges and piping and from 
spray freezing on the deck. 

In the DUKW, the exhaust air from the engine 
cooling system is used as a source of considerable heat 
for cold-weather operations, since the air discharged 
from this system is generally at a temperature of more 
than 150 F, even in extremely cold weather. This air 
blows into the forward compartment and ordinarily 
is then discharged through ducts at each side of the 
cab. These outlets, however, are fitted with shutters 
which can close them to any desired degree; a canvas 
cover is also furnished to close the normal air intake 
grating; and, in addition, the cockpit coamings are 
extended below the deck to form a heating duct com¬ 
municating with the engine cooling air outlets. If the 
dampers on each side leading to these coaming ducts 
are opened, the warm air is forced back to warm the 
hull sides, the side decks, and the cargo compartment, 
and then is discharged into the stern compartment 
and down below the floor to warm the bilge (Fig¬ 
ure 23). 

Other heating lines, running from the left air out¬ 
let passage directly to the bilge pumps and the for- 



A ENGINE RADIATOR G AIR EXHAUST GRILLE COVER 

B ENGINE COMPARTMENT H RECIRCULATING DUCT 

C AUXILIARY AIR INTAKE DAMPER DOOR 

D AIR EXHAUST GRILLE I RECIRCULATING HOT AIR DUCT 

E AIR INTAKE GRILLE J CARGO COMPARTMENT 

F DRIVER'S COMPARTMENT K STERN COMPARTMENT 

l AIR INTAKE GRILLE COVER 

Figure 23. Diagram of cooling and heating system in pro¬ 
duction DUKW. Intake (C) shown on forward deck was 

soon permanently closed in the field and later removed 

in production. 

ward bilge pump manifold, carry enough hot air to 
keep the pumps well above the freezing point. 

A defroster, developed for both straight and slop¬ 
ing windshields, uses radiator fan exhaust air coming 
from the right-hand air outlet duct in the driver’s 
compartment. This completely demountable unit is 
furnished in special kits and is not issued on all 
DUKWs. 

The battery is located in the engine compartment 
in order to receive cool air in warm weather and 
warm, recirculated air in cold weather. 

Tires 

The CCKW truck, the parent vehicle of the 
DUKW, has 7.50x20 dual tires on the rear and inter¬ 
mediate axles, with singles on the front axle. This 
combination was tested on the first pilot model of the 
DUKW, performing relatively well in slippery mud 
but very poorly on sand. 

Accordingly, sand tests were run on a number of 
identical CCKW trucks loaded to give DUKW axle 
weights and equipped with the following tire com¬ 
binations: 

1. 7.50x20 duals on rear and intermediate, singles 
on front—standard military snow and mud tread. 

2. 8.20x20 duals on rear and intermediate, singles 
on front—standard civilian truck tread. 




















































28 


THE DUKW: ITS DEVELOPMENT 






Figure 24. 11.00x18 ten-ply desert tread tires used on 
production DUKW. 

3. General 38-inch Air Cats, singles—shallow dia¬ 
mond tread. 

4. 10.00x20 singles, 12-ply—standard civilian tread. 

5. 11.00x18 singles, 12-ply—standard civilian tread. 
It was obvious immediately that neither the 7.50 

nor the 8.20 duals could compare with any combina¬ 
tion of single tires. The Air Cats gave the best all- 


around performance on sand and had low rolling re¬ 
sistance, but their great width made steering difficult 
and considerably reduced both maximum turning 
angle and water speed. They were also reported to be 
vulnerable to bruising and rim cuts. 

The 11.00x18 appeared to be slightly better than 
the 10.00x20 and was finally adopted with 10-ply 
construction and desert tread (Figure 24). This, of 
course, entailed the production of special wheels, 
rims, and beadlocks. 

An important result of these early tire tests was the 
doctrine of a particular tire pressure for a particular 
terrain—10 pounds pressure for soft sand, 30 pounds 
for coral, and 40 pounds for hard roads. Ample field 
experience later indicated the validity of this original 
doctrine, with the amplification that very soft terrain 
may require a pressure as low as 5 pounds. 

Controllable Central Tire-Inflation System 

To take advantage of these different pressures, it 
was necessary to provide an engine-driven, engageable 
air pump, which was made standard on all DUKWs 
(Figure 25). Two extension hoses were supplied so 
that two tires could be inflated at the same time. The 
use of this simple equipment, however, made it neces¬ 
sary to stop the vehicle and, under combat conditions, 
expose personnel to enemy fire. Accordingly, in July 


Figure 26. Early proposed hub arrangement for central 
tire-inflation control. 


Figure 25. 


Air pump used in central tire-inflation system. 









DESIGN PROCEDURE 


29 



Figure 27. Proposed two-line system, with housed, wire-actuated valve-in-stem. 


1942, OSRD requested an investigation of centrally 
controlled inflation systems which could be operated 
from the driver’s position while the DUKW was in 
motion. 

At first, tests were conducted on a single-hose type 
with a two-way valve in the stem of each lire (Figure 
26). The valve is opened by engine vacuum for deflat¬ 
ing anti by the tire pump pressure for inflating. Air 
enters through the external end of the hub and passes 
from a rotating hub gland through a copper tube to 
the tire valve. The tire valve is actuated by wire. This 
system was abandoned because the deflating air up¬ 
sets the intake manifold vacuum. 

The second system, also a single-line type, works on 
the same principle except that the escaping air in de¬ 
flating is released to the atmosphere, and the valve is 
moved from the tire stem to the hub unit and actu¬ 
ated by a cam-operated bell crank. 

Fhe third (Figure 27) involves a two-line system, 
with pressure in one line for deflation and in the 
other for inflation, together with a housed, wire- 
actuated valve-in-stem, as in the first design. 

All three of these systems, having individual valves, 
“fail safe”—that is, pressure is maintained in the tire 
even if the hose is torn off. None of these proposals 
was found sufficiently practical for use. 

The final system, which was actually put into pro¬ 
duction, is a single-hose type with tire valve cores re¬ 


moved (Figure 28). A permanent air line leads to each 
tire through a rotating gland on each hub (Figure 29), 
permitting the driver to vary the pressure from the 
dashboard while the vehicle is in motion, either on 
land or afloat. All tires thus have equal pressure auto¬ 
matically. The system (Figure 30) includes an air 
pump running constantly with the engine, an air 
tank, a gage, a pressure regulator, a control valve for 
inflation and deflation, hose for emergency use or 
for inflating the tires of other vehicles, and six valves 
with which the driver can shut off the line to any tire 
(Figure 31). If an external line is damaged, the tire 
connected to it will go flat. As a safeguard to the re¬ 
maining tires, any one line or group of lines can be 
segregated from the system by these internal valves 
operated by the driver. This system makes an ordi¬ 
nary tire fairly “bullet-proof.” For example, 28 .45- 
caliber slugs were fired into a tire which, backed up 
by the compressor, maintained sufficient pressure for 
ordinary use. 

Brakes 

Constantly submerged during water operation and 
periodically flushed with sand and salt water during 
surf and beach operation, the wheel brakes on the 
DUKW required considerable modification. The 
brake drums were mounted on the outside of the 
hubs to facilitate maintenance. Brake cylinders, end 





























30 


THE DUKW: ITS DEVELOPMENT 



Figure 28. .Single-hose, central tire-innation arrangement adopted for production. 


caps, and adjusting screws were plated with zinc 
chromate to resist corrosion. Brake return springs 
were rustproofed and the hooked ends improved. A 
search for a more suitable lining led to the selection 


Figure 29. Cutaway of rotating gland used on each hub 
in final central tire-inflation system. 


of Thermoid 908-B composition, which represented 
the best compromise for stopping with either wet or 
dry brakes. 

Superstructure and Surf Protection 

Early surf trials disclosed serious inadequacies of 
the superstructure, including the windshield, deck- 
mounted accessories, and cargo cover supports. First 
to fail under severe surf impact were the windshield 
and the surf plate: windshield frames bent and glass 
cracked, while surf plate braces bent, hinges tore 
loose, and plywood splintered. 

A temporary field modification kit for the wind¬ 
shield was first designed for visibility over its top 
edge, but the surf continued to smash the partly ex¬ 
posed glass and to bend the metal (Figure 32). The 
modification kit was revised to extend full height, 
with peek holes for the driver (Figure 33), and this 
gave adequate protection. In the meantime, the wind¬ 
shield was redesigned and surf-tested, resulting in the 
sloping front and side panels finally adopted (Figure 
34). 

The first surf plate (Figure 35), made of unrein¬ 
forced plywood, together with its piano hinges and 
brace rods, similarly failed under surf impact. The 
plywood plate was finally replaced by a reinforced 
steel plate, the brace rods were strengthened with a 
reinforcing channel, and the piano-type hinge was re¬ 
placed by four heavy hinges (Figure 36). 


















DESIGN PROCEDURE 


31 



Figure 30. Central tire-inflation control system, including air pump, air tank, gage, control valve, and emergency hose. 


The cargo bow, made of ash strakes joined with 
light sheet-metal stampings (Figure 37), likewise 
failed in operation, collapsing when hit by heavy 
surf. Ridge poles were issued as a temporary field 
modification, followed immediately by the substitu¬ 
tion of an all-steel, tubular bow, strong enough to 
withstand surf impact (Figure 38). This new bow was 
sealed to make it float if lost overboard. 

Since heavy following seas would occasionally roll 
over the coaming, it was raised at the rear and a ply¬ 
wood closure with side wings was added to resist the 
surf impact (Figure 39). The plywood structure, how¬ 
ever, proved to be awkward and rarely needed and 
was replaced by a canvas closure (Figure 40). 

In the initial design of the DLIKW, no definite pro¬ 
posal was made for hull protection at shipside except 
for the specification of 12 fender eyes placed at ran¬ 
dom. Field tests soon indicated that more adequate 



Figure 31. Dashboard controls for central tire-inflation 
system. 



Figure 32. Effect of surf impact on windshield reinforced 
with early field modification kit. 



Figure 33. Peephole windshield cover used as later field 
modification. 











































































THE DUKYV: ITS DEVELOPMENT 


32 



Figure 34. Final production windshield developed to 
withstand surf impact. 


protection was necessary, and the original lender eyes 
were relocated and the number of fenders increased 
from 6 to 8. A system involving the use of 6x24-inch 
marine rope fenders was standardized, and the addi¬ 
tion of a recommended ninth fender was approved. 



Figure 35. First surf plate made of unreinforced plywood 
and secured with piano hinges. 



Figure 30. Final steel surf plate with heavy hinges and 
improved brace rods. 


(This ninth fender was never issued.) The final pro¬ 
duction fender is a coir fender which can occasion¬ 
ally be worn out in approximately 1 day of opera¬ 
tion. Although OSRD recommended in January 1943 
that this be dropped in favor of a continuous rope 
fender in a chilled steel collar built in to follow the 
edge of the hull, the Army considered that the gains 
from this modification would be more than offset by 
the disruption to production, and turned down the 
change. Later experience indicated that the disrup¬ 
tion in the field caused by the lack of this modifica¬ 
tion was no minor matter: the coir fenders were in¬ 
herently unsatisfactory, the specified quality of the 
material was constantly revised downward, and the 
resulting maintenance problems were tremendous. 
A significant number of DUKWs suffered serious hull 
damage because of these inadequate fenders, an un¬ 
necessarily heavy load was placed on maintenance 
crews, and the total cargo carried by some DUKW 
companies was drastically reduced. 

Lifting, Davit, and Mooring Eves 

Experiments were made with lifting slings adapt¬ 
able to ship’s boom handling and to ship’s davits. 
Four lifting eyes were welded into the side of the deck 
and a set of davit eyes incorporated. Field tests indi¬ 
cated a need for a mooring eye, which was added 
amidships on each side. 

Winch 

The DUKW winch is similar to that on the CCKW 
truck except that it is located on the stern with lead 


Sk. 



Figure 37. Steel-jointed wooden cargo bows deformed by 
surf impact. 
























DESIGN PROCEDURE 


33 



Figure 38. Final all-steel bows. 


holes installed in the rear coaming and below the 
windshield, together with a fair-lead on the bow, to 
permit the cable to be led out either forward or 
astern. For better maintenance, the hole for the shear 
pin is made slightly larger and in later models the 
hatch in the rear deck is reversed, making the shear 
pin more accessible. 

Sand Anchor 

Tests of several types of anchor led to the selection 
of a 70-pound Danforth lightweight marine anchor 
for use in enabling a DUKW to free itself with its 
own winch as well as in anchoring at sea. This self- 
burying anchor is furnished as standard on all 
DUKW units. 



Figure 39. Rear plywood closure used in early models. 


On-Vehicle Equipment 

In addition to equipment already discussed, the 
DUKW carries a large assortment of tools and spare 
parts. Initially there was little precedent to suggest 
what should be carried, but field tests and early tacti¬ 
cal use quickly indicated the most necessary items. It 
was realized that if the DUKW were to be an im¬ 
portant link in the establishment of a beachhead, it 
should not be handicapped by the absence of neces¬ 
sary tools. Also, since there would be no repair facili¬ 
ties for some time after a beach landing, certain spare 
parts should be carried on every vehicle. 

As a result, pioneer tools, fire extinguishers, canvas 
buckets, a boat hook, and a large selection of hand 
tools are included as on-vehicle equipment. Spare 



Figure 40. Rear canvas closure used in later models. 


^ „ JLJ a ^-Fii >EN ¥h\ Irr 



















34 


THE DUKW: ITS DEVELOPMENT 



Figure 41. Side view of 1944 production DUKW. 


parts include gaskets, drain plugs, rudder and winch 
shear pins, distributor parts, brake hoses, bearings, 
tire-inflation parts, pump chain links, set screws, keys, 
a hull patch plate, caulking compound, wire, tape, 
and sandpaper. 

3-4 TEST PROCEDURE 

Routine tests for performance and reliability were 
conducted during the early part of the investigation 
on the first pilot models and also on various compo¬ 
nents and proposed design modifications. 

Measurements were made of maneuverability and 
speed on land and in water, economy, stability, grade 
ability, and general performance. Most of these tests 



Figure 42. Front view of 1944 production DUKW'. 


were conducted at Crystal Lake, Pontiac, and at the 
General Motors Corporation Proving Grounds at 
Milford, Michigan. Special surf tests were conducted 
on beaches in Virginia, Massachusetts, North Caro¬ 
lina, and California, and tests over coral on the Flor¬ 
ida Keys and later on Funafuti. 

Throughout all tests, engine performance was care¬ 
fully noted so that some temporary fluctuation would 
not lead to false conclusions on the efficiency of hull 
design or other components. 

As noted above, major hull design changes were 
studied on scale models in towed and self-propelled 
tests. 

3-5 RESULTS 

3 - 5 -' Design 

The 1944 production model of the DUKW is illus¬ 
trated by Figures 41 to 44, while Table 1 indicates the 
major differences between the first cab-over-engine 
pilot model built in 1942 (in 38 days from the “go 
ahead’’ order to the date on which it was driven out 
of the shop for field tests), the 1944 production 
DUKW, and the parent CCKW truck. 1011 

Much help in the development of the DUKW was 
derived from the fact that many basic problems had 
already been solved in the conversion of the l/^-ton 
jeep into its amphibious counterpart.•> In the DUKW 
program, building around a well-developed basic 
unit made it possible for more than two-thirds of the 
parts to be incorporated as items well past the devel¬ 
opment stage and already of proved field reliability. 
The original basic design proved to be sound, and no 

J See C,hapter 2 in this volume. 


































RESULTS 


35 



Figure 33. Front and side view of 1944 production DUKW, showing shape of bow. 


Table 1. Comparison of Specifications of 1942 Pilot Model 
DUKW, 1944 DUKW, and 1944 CCKW. 



1942 

Pilot 

Model 

DUKW 

1944 

DUKW 

1914 

CCKW 

Over-all length (in.) 

358 

372 

-70(4 

Over all width (in.) 

96 

98 

88 

Over-all height —top and 
windshield up (in.) 

99:/, 

106 

109(4 

Over-all height—top and 
windshield down (in.) 

8411 /ir, 

89 

76 

Wheelbase (in.) 

164 

164 

164 

Ground clearance (in.) 

17 

18 

17(4 

Tread —front (in.) 

60 K« 

637/g 

00 74,; 

Tread—rear (in.) 

67(4 

637/s 

67(4 

Cargo floor area (sq ft) 

78 

85 

80 

Tire size 

7,50x20* 

11,00xl8t 

7.50x20* 

Engine displacement 
(cu in.) 

269.5 

269.5 

269.5 

Net engine horsepower 
(2.750 rpm) 

93 

93 

93 

Weight light (lb) 

13,900 

14,880 

11,050 

Weight of driver (lb) 

200 

200 

200 

Pa)load (lb) 

5.000 

5,000 

5,000 

Weight loaded (lb) 

19,100 

20,080 

16.250 


* Dual tires, rear and intermediate wheels, 
t Single tires throughout. 


major changes became necessary. OSRD, however, 
exerted the greatest possible pressure to eliminate 
those faults which, however minor, could neverthe¬ 
less cause a vehicle to abort. k 


fc For a discussion of these modifications, see Chapter 4 in 
this volume. 


3 - 5 - 2 Performance 

Land Performance 

In many respects the 1944 DUKW amphibian can 
equal, and in some cases surpass, the performance of 
the comparable 1944 CCKW truck (Table 2). Each 
vehicle has roughly the same maximum speed and 
minimum turning diameter; the angle of approach is 
greater in the DUKW, the angle of departure is less, 
and the DUKW can negotiate slightly less steep 
grades because of its greater gross weight (Figure 45). 

Numerous field tests showed that the DUKW can 
operate successfully on hard roads and sand (Figures 
46, 47, and 48). For sand operation, tire pressure be- 



Fjgure 44. Rear view of early 1944 production DUKW. 

















36 


THE DUKW: ITS DEVELOPMENT 


Table 2. Comparison of Performance of 1942 Pilot Model 
DUKW, 1944 DUKW, and 1944 CCKW. 


. 

1942 

Pilot 

Model 

DUKW 

1944 

DUKW 

1944 

CCKW 

Maximum land speed (2,750 rpm) 

(in mph) 

Reverse—low 

2 

3 

9 

Reverse—high 

6 

7 

6 

First—low 

2 

3 

9 

First—high 

6 

7 

6 

Second—low 

4 

5 

4 

Second—high 

10 

11 

10 

Third—low 

9 

10 

9 

Third—high 

20 

22 

20 

Fourth (direct)—low 

16 

18 

16 

Fourth (direct)—high 

37 

40 

37 

Fifth (overdrive)—low 

20 

22 

20 

Fifth (overdrive)—high 

45 

50 

45 

Maximum water speed (mph) 

Reverse 

1 

2.5 

— 

Second 5.4 

Minimum turning diameter—land (ft) 

6.4 

— 

Left turn 

681/2 

70 

68/ 

Right turn 

681/2 

68/2 

68/ 

Minimum turning diameter—water 

(ft) 

Left turn 

140 

40 

— 

Right turn 

75 

40 

- 

Angle of approach (deg.) 

38 

38 

31 

Angle of departure (deg.) 

28 

25 

36 

Maximum grade ability (%) 

60 

60 

65 

Cruising range, full throttle—land 

(approx.) (miles) 

250 

250 

275 

Cruising range, full throttle—water 

(approx.) (miles) 

32 

40 

— 



Figure 45. First pilot model DUKW climbing 60-degree 
grade at Milford, Michigan. 


comes of particular importance: a pressure of 30 to 40 
pounds causes the tires to dig in, while a pressure of 
10 to 12 pounds lets the tires obtain ample traction 
(Figure 49). 

Operation on Coral. Even after military interest in 
the DUKW was well aroused, little thought had been 
given to the problem of driving this vehicle on coral 



Figure 46. Desert tread tires, correctly deflated, enable 
DUKW to climb sandy hills. . . . 



Figure 47 .clear the summit 




















RESULTS 


37 



Figure 49. Diagram showing effect of tires in soft sand when they are deflated to about 10 pounds (left), as compared 
to tires at 30 pounds (right). 


reefs, which front approximately 85 per cent of the 
shore lines in tropical Pacific waters. If DUKWs were 
to be used there, it was essential to learn how success¬ 
fully they could be operated on such reefs. 

Accordingly, in February 1943, OSRD conducted 
a series of tests with two DUKWs on various types of 
coral in the Florida Keys. These tests proved conclu¬ 
sively that, if a special coral-driving technique be 
carefully followed, a DUKW can be run almost in¬ 
definitely on the worst coral without serious damage 
to the tires or hull, and without additional wear at¬ 
tributable to coral (Figure 50). 

Briefly, this technique involves the use of the low¬ 
est possible speed, considerable skill in selecting the 
best available route, and a tire pressure of 30 pounds. 
This figure was determined after a study of the effects 
of coral on tires inflated at various pressures. With 
too high pressure, it was found, the tire develops 
bruise breaks because of the weakness of the cords 
in the ply when under heavy tension. With too low 
pressure, the tire walls develop rim crushes and also 
sag so that they are exposed to shearing cuts. At 30 
pounds, the tire is sufficiently soft to absorb the jabs 
of the coral points, and yet is firm enough that it is 
not forced against the wheel rim when passing over a 
sharp lip. In fact, when a DUKW is operated by a 
well-trained driver, the tires will receive less damage 
from coral reefs than will the tracks on a track-laying 
vehicle. 

On the northern beaches at Okinawa, DUKWs 
were obliged to traverse several hundred yards of bad 
coral many times a day for 4 months. As a result of 
OSRD training and supervision, the drivers followed 
the standard operating procedure for this terrain and 


thereby prevented any increased tire wear attribut¬ 
able to coral. 

Alternate Gear Combination. During the early 
phases of the development, it was felt that more effec¬ 
tive power was needed to improve beach perform¬ 
ance. Since the engine could not be readily changed, 
an alternate gear combination was considered in 


Figure 50. DUKW tires at 30-pound pressure successfully 
cross coral in tests on Florida Keys. 


GDNFXDS NTJAU- 
















38 


THE DUKW: ITS DEVELOPMENT 



Figure 51. Minimum turning diameter in water is 75 to 1 10 feet lor 1942 pilot model Dl'KW, 10 leet for production 
model shown here. 


order to give lower ratios with the otherwise standard 
transmission. 

The approximate comparative road speeds to be 
obtained with the two types is shown in Table 3, with 
power in approximately inverse proportion to the in¬ 
dicated maximum speeds: 


Table 3. Maximum Load Speeds (mph) at 2.750 Engine rpm. 



Standard CCKW 
type 

Proposed 

“underdrive” 

type 

Gear 

High 

Low 

High 

I .ow 

5 th 

50 

22 

40 

18 

-nil 

-10 

18 

23 

10 

3rd 

22 

10 

13 

6 

2nd 

11 

5 

9 

4 

1st 

/ 

3 

r> 

3 

Reverse 

7 

3 

7 

3 


Although the recommended alteration was not ap¬ 
proved for reasons of production, maintenance, and 
driving simplicity, and because the change in tires 
gave improved sand performance with the CCKW 
transmission, the wisdom of this decision was later 
questioned. 

In retrospect, particularly in view of the heavy 
overloads which were habitually carried and the in¬ 
creased hull weight, it appears that the nonstandard, 
“underdrive” transmission would have been more de¬ 
sirable. 1’he CCKW shift pattern is unusual and rela¬ 
tively inconvenient. There would be less spread from 
the ratio of second speed to reverse. The lower ratio 
second speed would frequently obviate the necessity 
of using first speed, except when the vehicle is stuck. 
The lower ratio transmission would provide speeds 
better suited to the majority of landing operations. 
Although the present transmission provides a theo¬ 
retical top road speed of 50 mph, this is practically 
never used under field conditions. 


Water Performance 

The water speed of the DUKW, greatly affected by 
the resistance of the hull and the various appendages, 
was increased by about 30 per cent as a result of de¬ 
sign improvements. In preliminary tests, the maxi¬ 
mum speed was 5.0 mph. Decreasing the size of the 
propeller increased it to 5.35. Reducing the power 
requirements of the fan, introducing down draft car- 
buretion, tuning up the engine, and adjusting the 
valves brought it up to 5.75. Adding 18 inches to the 
stern and moving the propeller 15 inches astern in¬ 
creased it to 6.3. Providing covers for the front wheel 
houses increased it to 6.4. And, finally, improving the 
propeller and drive ratio brought it up to 6.5. 

A further increase of perhaps 0.4 mph could the¬ 
oretically have been obtained by using a retractable 
propeller, but it was felt that the actual net average 
gain for a DUKW fleet over a period of time might 
be nil, as a result of the probable frequency of dam¬ 
age to the blades. Further increases up to 0.4 mph 
could theoretically have been made by omitting the 
governor, using a slightly different shape of propeller, 
and adding additional fairings and covers, but these 
changes would have involved too many mechanical 
and operating difficulties. 

The turning circle of the production DUKW in 
water—about 40 feet—is larger than that of some 
other landing craft, but is not excessive for maneu¬ 
verability (Figure 51). 

Surf Performance. Many field tests proved the 
ability of the DUKW to negotiate cpiiet lake water, 
open sea, and surf. When the vehicle is operated by 
a trained driver, it can get through a surf up to 15 
feet high, and in tests has gone through surf some¬ 
what more than 20 feet high without difficulty. 

Fhe DUKW was repeatedly found to be inherently 
stable in the surf. Its center of gravity is low, largely 






















RESULTS 


39 



Figure 52. Series of photographs of laden DUKW penetrating 15-foot comber on steep-to beach at Monterey Bay, 
California, showing very rapid rise of bow due to shape and buoyancy of bow sections. Last picture shows course 
unaltered. Amount of water taken aboard is ejected by pumps in about 1 minute. 













40 


THE DUKW: ITS DEVELOPMENT 



Figure 53. Series of photographs showing laden DUKW standing out through solid afterbreak of 15-foot comber on 
steep-to beach at Monterey Bay, California. Course is deliberately somewhat diagonal and is unaltered. Speed is tem¬ 
porarily reduced from about 4 knots to about 1 knot. 


^^eSNFfDrENTTAL 













ACCESSORY EQUIPMENT 


41 



Figure 54. DUKW surf ability tested in moderate surf at Monterey Bay, California. 


as the result of the location of three heavy axles 
below the bottom of the hull. Its deck weight is light 
and its cargo rests in a relatively low position. Its 
hull has extremely full and well-balanced ends. Dis¬ 
placement is large as compared to freeboard and, 
as a result, the DUKW can go through a wave which 
would knock a lighter boat toward the beach. 

When the DUKW lands with the surf, the hull 
resistance created by the numerous appendages holds 
the vehicle down to a safe speed. It seldom goes very 
far on one wave, although in extreme cases it has 
gone somewhat more than 100 yards. Rudder steer¬ 
ing is used during a landing, and the front wheels 
provide some steering when the propeller and the 
rudder may be temporarily out of water. The low 
reserve buoyancy minimizes any tendency to lift the 
rudder or propeller. As shallow water is reached, sta¬ 
bility is derived not only from the fact that there are 
wheels along each edge but also from the ability to 
steer at each end—with rudder in back and wheels in 
front. 

The major surf tests were conducted off Kitty 
Hawk, North Carolina, on June 25, 1942; near Prov- 
incetown, Massachusetts, in November and Decem¬ 
ber 1942; off Virginia Beach, Virginia, in January 
1943; and off Fort Ord, California, in January and 
March 1943. 

Off Kitty Hawk, the tests were run on the first pilot 
model in a 6-foot surf. The engine ignition system 
was not waterproofed, the cab-over-engine structure 
exposed the engine, and the steering was inadequate. 
As a result, the DUKW came broadside to the surf 
and the engine was drowned out, but the DUKW 
was not swamped. It was retrieved and driven across 
country to Pontiac, Michigan. 

In the tests at Provincetown and Virginia Beach, 


an improved model was used in a 7-foot surf and op¬ 
erated quite successfully, making repeated trips in 
and out of the surf. Major failures were the wind¬ 
shield and bow surf plates. 

At Fort Ord (Figures 52 to 54), DUKWs with still 
more improvements were used in OSRD-supervised 
training in 15-foot surfs and, in tests, in higher surfs, 
and again operated successfully even under these 
conditions. Windshield, bow surf plate, and cargo 
bow failures still occurred but were finally mini¬ 
mized by modified structures. 

Possibility of Strategic Surprise. These tests and 
the improvements they brought forth soon became 
of paramount tactical importance, since they made 
it possible for the DUKW to be used in a surf so 
heavy that no other amphibian or boat could operate. 
Both American and British Services were thereafter 
repeatedly urged to plan operations around this abil¬ 
ity of the DUKW and to land at places and in 
weather which the enemy would certainly consider 
impossible for landings, thus achieving tactical and 
possibly strategic surprise. 

36 ACCESSORY EQUIPMENT 

The mechanical development of the DUKW was 
accompanied by the conception of several special 
missions for which the new vehicle could be em¬ 
ployed. In many of these cases, special equipment 
was designed and constructed to facilitate loading 
and unloading the DUKW, to enable the DUKW 
to ferry tanks and trucks, and to adapt it to combat 
operations. In some cases, the equipment was de¬ 
signed but, because of changing military require¬ 
ments, not investigated further. In others, the 
equipment was designed and built but not approved. 


^-Cf^NF XDEN T IAD-—— 










42 


THE DUKW: ITS DEVELOPMENT 


or approved but not put in production, or put in 
production but never delivered to the forward areas. 
(See Chapter 4.) 

In the case of such of those missions as were carried 
out in the field, standard operating procedures were 
developed on the spot in collaboration with the 
Services. 

361 Cargo-Handling Equipment 

A-Frame 

In November 1942, a tactical doctrine was de¬ 
veloped whereby DUKWs would carry 105-mm ho¬ 
witzers front ship to shore, unload them by A-frames, 
and tow them into battery position. The first such 
A-frame was improvised in the field for the Province- 
town, Massachusetts, demonstration (see below) from 
cedar timbers with temporary steel fittings (Figure 
55). This was soon improved and an A-frame made of 
round steel tubing went into production (Figure 56). 
Few of these production A-frames reached combat 
areas in the European and Mediterranean theaters 
before V-E Day, however, and the A-frames actually 
used in those areas had to be improvised on the spot 
from whatever materials were at hand. 

Pallets and Palletized Loads 

In order to obtain maximum use of the DUKW' 
cargo space and to facilitate cargo handling, a 
DUKW pallet was designed early in 1943. This pallet 
consisted of a wood platform with canvas webbing 
sides to contain the cargo and a four-part wire sling 
on a lifting ring. Later, since webbing was almost 
unobtainable, it was replaced by rope net. 

Tests proved that this pallet was of some help to 
DUKW' cargo-handling operations but it received 
only little interest. In spite of its advantages, it was 
elaborate and bulky, and it still did not solve two of 
the main problems: easing the burden of cargo-han¬ 
dling personnel at the ship unloading point and 
speeding up the flow of cargo during the assault 
phase of an amphibious operation. 

At this time, however, some interest was being 
shown in the palletization of certain assault cargo, 
such as field rations and ammunition, by securing 
it with steel strappings to a wooden platform 
mounted on runners. Palletized loads could be made 
up at the ports of embarkation or even at the fac¬ 
tories, making it possible to save manpower and 


time in the forward areas where these factors were 
most vital. 

In several operations, a limited amount of pallet¬ 
ized cargo was used with great success, but this was 
strongly opposed by the Navy because the bulk of the 
pallet itself reduced the amount of supplies that 
could be carried in a ship. With the greater avail¬ 
ability of shipping in 1944, however, more demands 
for palletized loads were made and in the Kwajalein 
operation the majority of rations, ammunition, and 
fuel were palletized. 

The dimensions of the pallet had been set at 48x72 
inches, but these were not ideal since only two loads 
could be fitted into the DUKW cargo space. Another 
objection was based on the excessive amount of wire 
cable required to make the two slings for lifting and 
towing each load. 

Accordingly, a new palletized load was developed 
by OSRD at Oahu early in 1945. This load had over¬ 
all dimensions of 44x70 inches, which enabled three 
loads to fit into a DUKW. It was found, incidentally. 



Figure 55. Emergency A-frame improvised from cedar 
timbers for demonstration at Provincetoivn, Massa¬ 
chusetts. 


■AL 











ACCESSORY EQUIPMENT 


43 



Figure 56. Steel tubing A-frame adopted for production, 
shown here with improvised outriggers attached to 
DUKW to provide added stability for “A-framing” afloat. 


that these dimensions were also better suited to a 
variety of other carriers, such as the 2y 2 -ton truck 
and the LVT(4). To dispense with permanent slings 
on each load, lifting eyes were fitted at each of the 
four corners, making it possible to lift the load with 
a four-part sling which was unhooked and remained 
on the cargo hook (Figure 57). 

A variety of supplies palletized in this manner 
were demonstrated on Oahu to staff representatives, 
and the system was approved by Headquarters, U. S. 
Armed Forces, Pacific Ocean Areas, and later by 
Headquarters, Army Forces, Pacific. It was not put 
into use, however, before the end of World War II. 

Transfer Rigs 

When DUKWs began to operate on a large scale 
on big land masses, it was found that their amphibi¬ 
ous values were often being largely wasted and, par¬ 
ticularly when the unloading points were more than 
4 or 5 miles inland, the amphibians were spending 
most of their operational time as land trucks. In 
such cases, an excessive number of DUKWs was re¬ 
quired to maintain a cycle which would not cause 
delay in getting the cargo off the ships. 

Consequently, a standard operating procedure 
was developed, based on the use of a transfer point 
system so that loads could be transferred from the 
DUKW to a land truck close to the DUKW landing 
point and the trucks then used to make the long 
haul. Several types of transfer rig were used, the 
commonest being 5-ton mobile cranes and DUKW 
A-frames (Figure 58). DUKWs deadlined for water 
operation because of propeller or hull damage could 
be used as transfer rigs so that seaworthy DUKWs 
would not be tied up. 



Figure 57. Palletized cargo being loaded into DUKW at 
Oahu with aid of four-part sling. 


Other rigs included a high lift on a truck, a high 
lift on a platform, and an A-frame on a land truck. 
In the Normandy landings, several of these types of 
transfer rigs were used on a large scale. In addition. 



Figure 58. Mobile crane lifts cargo from DUKW: simple 
transfer rig used in Southwest Pacific. 


---CON4T^TNT^Ai- 


















44 


THE DUKW: ITS DEVELOPMENT 



Figure 59. Transfer rig arrangements used to transfer cargo from DUKWs to trucks in Normandy landings. 


a steel pipe platform developed by the Transporta¬ 
tion Corps was service-tested at Omaha Beach. At 
Okinawa, this standard operating procedure had be¬ 
come accepted and land hauls of more than 2 miles 
were made by truck. (See Figure 59.) 

3,6 2 Ferrying Equipment 

During the early part of the development pro¬ 
gram, considerable emphasis was placed on the de¬ 
sign and testing of many types of ferrying equipment. 
Particular interest had been expressed by the Chief 
of the Armored Force in the possible use of DUKWs 
to take light or medium tanks from shipside across 
water, sand bars, and coral reefs to a beachhead. Ac¬ 
cordingly, and as part of a systematic exploration of 
all fields in which DUKWs might be useful, tests 
were carried out with various types of cargo and with 
various types of ferrying equipment. 

These were never exploited beyond the experimen¬ 
tal stage, because better means for doing the same 
thing were developed by the Armed Services. 


Wet Ferry 

Preliminary analysis indicated that a pair of 
DUKWs should be able to ferry a light tank through 
water without difficulty. With two DUKWs forming 
a catamaran, being held in position with compres¬ 
sion struts at the decks and tension cables crossed 
from the lowest corners of the hulls, trials were con¬ 
ducted in a fairly shallow lake at the General Mo¬ 
tors Proving Ground in September 1942. A light 
tank was equipped with necessary sealing devices, 
attached to the DUKWs (Figure 60), carried across 
the lake (Figure 61), and discharged on the other 
side (Figure 62). 

Later, at the request of the Ordnance Department, 
similar trials were made with the medium tank, first 
in a lake and then in deep water. In the final trials 
off Fort Story, Virginia, preliminary runs were made 
with a dummy tank—four large water containers 
with quick-action dump valves. When these boxes 
were filled with salt water, they and their supporting 
platform weighed about 42,000 pounds, which rep¬ 
resents approximately the negative buoyancy of the 



Figure 60. Light tank being connected to two DUKWs for wet ferry across Sloan Lake at General Motors Corporation 
Proving Grounds, Milford, Michigan. 













ACCESSORY EQUIPMENT 45 



Figure 61. Wet ferry under way. 



Figure 62. Wet ferry completed: light tank climbing to dry land. 


medium tank. Sea trials showed the DUKWs could 
handle this load, but with little reserve buoyancy 
(Figure 63). 

A waterproofed medium tank was then attached 
to the DUKWs, carried to a ship standing more than 


a mile offshore, hoisted aboard, lowered again, and 
carried back to shore (Figures 64 to 67). 

Since the reserve buoyancy was dangerously low, 
however, a serious leak in any one of the three units 
would have been disastrous. The lack of freeboard 



Figure 63. Rehearsal of wet ferry off Fort Story, Virginia, with boxes of water as test load. 





















46 


THE DUKW: ITS DEVELOPMENT 



Figure 64. W et ferry test: medium tank supported by two DUKW's leaving beach at Fort Story. 



Figure 65. Ferry and tank nearing ship more than 1 mile offshore. 




Figure 66. End of ferry ride: tank at ship's side and sling 
made fast. 


Figure 67. Tank leaving DUKW ferry on way to ship's 
deck. 























ACCESSORY EQUIPMENT 


47 



Figure (38. Catamaran and Headway for dry ferry. 


would generally limit operations to relatively smooth 
water, with a maximum wave height of about 2 to 3 
feet. The project was ultimately dropped. 

Dry Ferry 

It soon became evident that nonsubmcrsible ve¬ 
hicles and goods could be ferried over deep water by 
using platforms or treadways erected on the same 


catamaran rig used for wet ferrying. Several types of 
treadways and loading ramps were designed and 
tested, with the best design providing a long loading 
ramp with the pivot point amidships so that the load 
is shared by all axles. The DUKW winches are used 
to raise the ramps, which then lock to front deck 
pintle hooks to form the sea-going platform. 

At sea trials off Fort Story, Virginia, the improved 



Figure 69. Army 6x6 truck backing up Headway for dry ferry test oil Fort Story, Virginia. 



























48 


THE DUKW: ITS DEVELOPMENT 



Figure 70. Truck at sea in test of DUKW dry ferry. 



Figure 71. Platform ferry requires simple equipment gen¬ 
erally available in field. 





Figure 72. Platform ferry entering water. 


rig was used in one test to carry a 6x6 truck from the 
beach to a ship standing a mile offshore (Figures 68 
to 70), in another to carry an armored half-track, and 
in a third to carry an M-3 light tank weighing about 
28,000 pounds. Reserve buoyancy was very low. 

Platform Ferry 

As a field improvisation, a platform was built across 
two DUKWs, which were then rigged together with¬ 
out use of special pintle hooks or reinforcements. 
The vehicles were lashed together at bow and stern 
by cables and turnbuckles, separated slightly by 
spacer blocks, and then used to support a platform 
laid across the cargo coamings and stabilized by 
timbered rails and cross rails secured to lashing eyes 
in the cargo space. The platform, which was designed 
and built in 3 days, successfully carried an armored 
half-track truck in deep water (Figures 71 to 72). 

Airplane Ferry 

In September 1943, after the DUKW had been ac¬ 
cepted and used routinely for cargo carrying, a re¬ 
quest was made by the Army to adapt this vehicle for 
ferrying the P-38 twin-engine and the P-40, P-47, P-51, 
and P-63 single-engine fighter planes from ship to 
shore. 

The basic catamaran construction, similar to that 
used earlier in the wet ferry for tanks, was employed 
in this new assignment, but with a greatly increased 
span necessary to accommodate the airplane’s land¬ 
ing wheels. For structural reasons, the plane was sup- 

















ACCESSORY EQUIPMENT 


19 



Figure 73 . P-38 fighter plane stowed mi ship’s deck with 
wing tips removed. 



Figure 75. P-38 secured on DUKW ferry. 


ported in troughs secured to the sides of the DUKW 
hulls. These troughs also acted as runways for rolling 
the plane to the stern, where specially designed 
ramps continued the treadway to the ground. 

With the P-38, it had been believed at first that the 
plane could not be safely loaded or unloaded with its 
wing tips in place, and these were removed for the 
first trials (Figures 73 to 77). Later trials showed that 
a better procedure is to moor the DUKW’s stern to 
the side of the ship, and in this position, since wing 
span is not critical, the wing tips can be left in place 
(Figures 78 and 79). 

These tests indicated that not only the P-38 but 
also other fighter planes could be ferried successfully. 



Figure 74. P-38 being lowered to waiting DUKW ferry 
ofF Hampton Roads, Virginia. 



Figure 76. DUKW ferry heading for beach. 



Figure 77. P-38 rolling down ramp to beach after DUKW 
ferry trip. 


































50 


THE DUKW: ITS DEVELOPMENT 



Figure 78. Modified mooring arrangement makes possible 
handling P-38 fighter plane with wing tips in place. 


T R actor-Trailer 

At the request of the Ordnance Department, rough 
plans were prepared for a large amphibious tractor- 
trailer to increase the capacity of the DUKW. 
Sketches were prepared for a two-wheeled, stern- 
ramp trailer, the necessary modifications to the 
DUKW stern, and a suitable hitch (Figures 80 and 
81), but no detailed plans were made and no pilot 
model was constructed. A smaller amphibious trailer, 
however, was designed and one test model was con¬ 
structed. 1 


i See Chapter 8 in this volume. 



Figure 79. P-38 with wing tips in place on way to beach 
by DUKW ferry. 


3.6.3 Ponton DUKWs 

In an attempt to provide a stable, powered unit 
for heavy-duty dry rafts and floating bridge supports, 
designs were prepared for coupling two DUKWs to¬ 
gether, first stern-to-stern and later bow-to-stern. This 
would provide a self-propelled unit, thus eliminating 
the need for extra transportation on land and for 
maneuvering cables and power boats or outboard 
motors in water. Test units were constructed (Figures 
82 and 83) and taken to the Imperial Dam on the 
Colorado River for study. As in the case of ferrying 
tanks and airplanes, the DUKWs were not seriously 
considered for use as pontons because of their greater 
need in other operations. 

3.6.4 Mat-Laying Equipment 

In May 1943, methods were developed for enabling 
the DUKW to lay a woven accordion-pleat wire land- 









Figure 80. Artist’s conception of proposed amphibious tractor-trailer unit. 
















ACCESSORY EQUIPMENT 


51 



Figure 81. Artist's conception of proposed tractor-trailer unit at shipside. 

ing mat 1 " somewhat similar to that used for air strips 
but much lighter. Its primary use would be to pro¬ 
vide lauding strips from the water’s edge across soft 
sand for the support of vehicles normally unsuited 
to soft sand operation. Presumably these matting 
strips would be laid by a DUKW just ahead of land¬ 
ing craft approaching the beach. The mat-laying 
device might also be used for laying a temporary take¬ 
off strip for airplanes engaged in emergency ferrying 
operations. 

In operation, the landing mat (Figures 84 and 85) 
would be drawn from its folded position in the rear, 
passed over the cab, and then spread under the front 
wheels by the forward motion of the vehicle. The mat 
would have to be hand-fed until the first section 
passed under the front wheels, after which the for¬ 

m Developed by Tri-State Engineering Company, Washing¬ 
ton, Pa. 



ward motion of the vehicle would furnish the neces¬ 
sary feeding power. Brake shoes on each side of an 
overhead guide frame would regulate the tension at 
which the mat would be laid. It was calculated that 



Figure 82- DUKWs secured in stern-to-stern tandem for 
ponton tests. 


Figure 83. DUKWs secured in bow-to-stern tandem for ponton tests. 















































52 


THE DUKW: ITS DEVELOPMENT 



Figure 84. Front view of DUKW equipped with proposed 
landing mat. 


one DUKW could lay from 200 to 400 feet of matting, 
depending on the roughness of the sea and other ex¬ 
ternal conditions. 

Preliminary engineering tests were conducted on 
the use of this device on the DUKW, but it was 
neither subjected to routine tests nor used in actual 
operations. 4 

3 - 6 - 5 Armament 

Gun Ring 

A gun ring mount already developed for trucks 
was adapted for the DUKW (Figure 86) by the War 
Department. 

The 105-mm Howitzer 

The successful use of the DUKW in transporting 
various weapons led naturally to the proposal that 
these weapons be so installed that they could be fired 
at sea or used as mobile artillery on land. 

After a protracted study with the 4.2-inch chemical 
mortar, it was found that this weapon could not be 
fired on the DUKW without the installation of a 
complicated, elaborate shock-absorbing system. Ma¬ 
jor emphasis was therefore placed on the 105-mm 
howitzer, and early in 1944 preliminary tests on an 
improvised harness were undertaken, first on land 
and then at sea (Figures 87 and 88). The results were 
sufficiently encouraging for OSRD to recommend 
further development and adoption of this combina¬ 
tion as a major addition to amphibious fire power. 
This recommendation, however, was tabled partly 
because of the expectation by the using Services that 
the LVT(A)(4), a larger and armored vehicle, would 
soon be available and would be superior to the 
DUKW, and partly because of human inertia, ft 



Figure 85 . Side view of DUKW equipped with landing 
mat. 


was later found that the new LVT, when it was finally 
delivered, could carry only a 75-mm weapon. 

Had the OSRD recommendation been accepted 
without delay, 105-mm fire power in DUKWs would 
have been available for atoll warfare from Kwajalein 
on. 

The 25-Pounder 

A similar harness for firing the 25-pounder, the 
British counterpart of the 105-mm howitzer, was de¬ 
veloped in India for use in an operation which was 
later cancelled. This form of amphibious fire power 
was not subsequently used, being superseded by 
rockets. 

The 3-Inch Antitank Rifle 

A similar harness was successfully developed for 
the 3-inch rifle (mounted on the wide 105-mm car- 



Figurf. 86. Standard gun ring mount adapted for use on 
DUKW. 
























DEMONSTRATIONS 


5.3 



Figure 87. 105-mm howitzer can be handled easily by 
DUKW to fire on land. 



Figure 88 . 105-mm howitzer on DUKW can also be fired 
at sea. 


riage). This was undoubtedly the heaviest weapon to 
be fired from a DUKW. it was not used in combat. 

It was found that the DUKW winch cable could be 
made to substitute for the harnesses for the 105-mm 
howitzer, the 25-pounder, and the 3-inch antitank 
rifle. 

Rocket Launchers 

Early in 1943, exploratory studies and field tests 
indicated that the DUKW could be used eflectively 
to carry launchers for the 4.5-inch beach barrage 
rocket. The cooperation of Division 3 of NDRC was 
obtained and an improved honeycomb-type, 120- 
rocket launcher was developed in collaboration with 
CMC Truck & Coach Division to replace the rail-type 
launcher then in use. 11 

Later, another type of launcher with a capacity of 
only eight rockets was tested for use on the rear deck 
of the DUKW. Lightly fastened to the vehicle, this 
launcher was found able to withstand single and 
ripple fire without difficulty and without harm to 
the DUKW. 

37 DEMONSTRATIONS 

3 - 7 - 1 Preliminary Demonstrations 

The first pilot model of the DUKW, completed in 

38 days, was displayed unofficially on June 2, 1942, 
and on June 12 it was demonstrated to a group of 
officers and civilians at the General Motors Corpora¬ 

11 For a more detailed report, see Chapter 16, Section 16.4, on 
Project “Scorpion.” 


tion Proving Grounds at Milford, Michigan. Its op¬ 
eration on land and in water had a good reception, 
which was erroneously interpreted as an indication 
of early acceptance by the Armed Services. Four days 
later, on June 16, it was apparent that the DUKW 
would not be accepted early or, possibly, at all. The 
pilot model was driven to Fort Belvoir, Virginia, and 
demonstrated to Army officers, including representa¬ 
tives of the Engineer Board, whereupon the Chief, 
Corps of Engineers, indicated that there was no need 
for such a vehicle and recommended that its further 
development be halted. In spite of this conclusion, a 
third demonstration was held at Fort Story, Virginia, 
on June 23. A slightly more dramatic presentation 
was arranged, with a mock troop landing (Figure 89), 
but the reaction of military observers was again un¬ 
sympathetic. 

Thus, after 3 weeks, a series of small, inconclusive 
demonstrations had made a few friends for the 
DUKW but had failed to stir the imaginations of 
senior officers. 

In the following weeks, other small-scale demon¬ 
strations and tests were conducted before official 
observers. On August 25 at Solomon’s Island, Mary¬ 
land, the reworked pilot model No. 1 was shown 
with the Ford i/^-ton amphibian and the Aejua- 
Cheetah of Hofheins; a similar comparison was made 
on September 16 at Camp Edwards, Massachusetts. 
Neither these nor other and unofficial displays re¬ 
sulted in the acceptance of the DUKW. The DUKW 
was either ignored or severely criticized for low water 
speed, difficulty of maneuvering, inability to get 
















54 


THE DUKW: ITS DEVELOPMENT 



Figure 89. Mock troop landing staged at Fort Story, Virginia, to demonstrate tactical usefulness of DUKW and 
amphibious jeejJ (at right). 


through surf, and unseaworthiness. There was a 
widespread conclusion that if the I)UK\V 7 could per¬ 
form a useful military function—which was doubtful 
—other vehicles could perform it better. 

Even though the DUKW could clearly travel 
where no other single vehicle could operate, such 
as in deep water interrupted by sand bars (Figure 90), 
its operational advantages remained generally un¬ 
appreciated. The DUKW 7 idea had not caught on. 

In the meantime, a most fortunate thing had hap¬ 
pened. The Chief, Development Section, ASF, had 
received a directive from the Chief, ASF, to provide 
means for speeding the discharge of Lend-Lease car¬ 
goes at places like Basra, where ships were waiting 
2 months before discharging into sailing lighters. 
Upon receipt of this directive, he was advised by the 
Chief of Division 12 of NDRC that 90 per cent of 
the world’s beaches can be crossed by a wheeled ve¬ 


hicle with the right tire pressure, and forthwith, 
early in June 1942, he initiated a production order 
for 2,000 DUKWs before they had been tested or re¬ 
ported upon by the War Department. This order, 
received by General Motors Corporation on July 
1, 1942, was presumably given, and certainly received, 
as an expedient—an emergency measure to employ 
something barely practical until a really useful logis¬ 
tical vehicle could be found. There was no assump¬ 
tion that such a production order meant acceptance 
of the DUKW as a vehicle acceptable to those mili¬ 
tary Services which could logically employ it on a 
large scale, and for the purposes outlined on page 13. 
On the contrary, it had become evident that none of 
the modest demonstrations conducted during the 
summer of 1942 had succeeded in satisfy ing the Serv¬ 
ices that the DUKW 7 could make important and ver¬ 
satile contributions to logistics or tactics. OSRD, 



Figure 90. OIF Provincetown, Massachusetts, DUKW demonstrates its usefulness in operating in deep water inter¬ 
rupted by sand bars. 


























DEMONSTRATIONS 


55 


therefore, decided to stake the future of the DUKW 
on a massive and dramatic demonstration, in the 
roughest weather obtainable. 

3 . 7.2 The Provincetown Demonstration 

Once the need had become clear, OSRD personnel 
and representatives of the two contractors started 
plans for such a demonstration to be given early in 
December. After a survey of the East Coast, Province- 
town, Massachusetts, was selected, since the backside 
of the hook was likely to have heavy surf and tide 
rips, while the shape of the incurving hook meant 
that on any given day any gradation of surf, from 
none to the maximum for that day, could be selected 
for training. Further, the water was generally too 
shallow for enemy submarines. It was determined 
that the program would include full-scale demonstra¬ 
tions of many actual applications of the DUKW and 
that the presentation would take advantage of rough 
winter weather rather than avoid it. 

Accordingly, with the assistance of Army, Navy, 
and Maritime Commission officials who were person¬ 
ally interested in the program, preparations began 
on October 30. A special detachment of officers and 
men —the first “DUKW company”—was assigned to 
OSRD by the Commanding General, Engineer Am¬ 
phibian Command, and started training to handle 
the DUKWs. Eight production models were requisi- 
tioned in addition to the four handmade pilot mod¬ 
els. Special loading problems were conceived, and 
special equipment and methods were designed to 
solve them. Dummy cargo was made up by the Army 
and a Liberty ship was assigned to OSRD for the per¬ 
formance. OSRD personnel with great experience in 
navigating small craft, particularly in surf, provided 
special training to the drivers, crews, and officers. 

For 30 days, this group developed and rehearsed 
its procedures in smooth and rough water, in surf, 
and in sand. It practiced mooring, loading and un¬ 
loading, and handling every variety of cargo that 
could be obtained or simulated. The training equip¬ 
ment consisted of a 5-ton Lorraine crane, lashed 
amidships in an LCT from which dummy cargo was 
discharged into DUKWs lying off her weather side 
while the LCT steamed at 4 knots into quartering 
winter seas off Peaked Hill Bar on the back side of 
Cape Cod. It was hoped that these conditions were 
more boisterous than would be found on the lee side 
of a Liberty ship even in fairly heavy weather. 1 his 


was found to be the case during the actual demon¬ 
stration and, although the weather was moderately 
rough, no difficulty was encountered. 

The actual demonstration was scheduled for De¬ 
cember 6 and 7. In the early morning of December 
2, however, the ability of the DUKW was tested in 
an unexpected dress rehearsal which became perhaps 
as important as any planned formal program. Shortly 
after midnight, a small Coast Guard patrol boat with 
her crew of seven men went aground on a sand bar 
about \/ A mile offshore on the northeast side of Cape 
Cod just inside Peaked Hill Bar. With the wind 
reaching a velocity of 60 mph, a hard, driving rain, 
and a good surf, the crew could not get ashore by 
swimming or by lifeboat or raft. Coast Guard per¬ 
sonnel from three shore stations arrived with rescue 
equipment, but the high wind, the surf, and the 
strong current made it too risky to use a surf boat 
and the breeches buoy was impractical. 

At the request of the local Coast Guard com¬ 
mander, two DUKWs were driven to the beach— 
about 15 miles from the demonstration headquarters 
—over roads and sand dunes. One DUKW was left 
on the beach for emergency. The other, driven and 
skippered by OSRD personnel and with two Coast 
Guardsmen as crew, went into the surf and out to the 
stranded vessel. Six minutes later, the DUKW re¬ 
turned with the seven crew members, dry shod, and 
carrying their personal gear. 

The entire operation was described as uneventful 
(Figures 91 and 92). 

Five hours later, at approximately 0630 hours, the 
rescue party returned to the spot to examine the 
vessel in daylight. The vessel, however, had disap¬ 
peared and no trace of her was reported during the 
next week. 

On the morning of December 6, the first of the 
two demonstration days at Provincetown, the official 
party of 86 officers from Washington, representing 
the Army, the Navy, the Coast Guard, the British 
Army, the Canadian Army, and the British Admi¬ 
ralty, arrived at Providence by train. They were met 
by buses and taken to Provincetown. 

The weather had been encouragingly rough dur¬ 
ing the previous days but its sudden tendency to 
moderate during the night of December 5-6 spelled 
disaster for the demonstration. A courier with the 
heavy clothing and boots for the party was therefore 
sent from Provincetown to intercept the buses at 
Orleans and request the officers to change their 





56 


THE DUKW: ITS DEVELOPMENT 



Figure 91. DUKW leaves beach on rescue mission off 
Provincetown, Massachusetts. 


clothes en route so that the demonstration might 
begin without delay on their arrival, and before con¬ 
ditions “improved any further.” 

It will be seen later that these deliberate efforts at 
dramatization may have been too successful. 

Under official observation for 2 days, the DUKWs 
proceeded to demonstrate their operational value. 
They repeatedly went through a moderate surf—the 
worst which could be located—and operated in a 
moderate sea with the wind at about 25 mph and 
waves ranging from 3 to 10 feet in height (Figure 93). 
Dummy cargo was taken on from the Liberty ship 
SS Carver, which was standing about a mile and a 



Figure 92. Coast Guard patrol boat with seven men 
aboard, aground on sand bar off Provincetown, Massa¬ 
chusetts. 


quarter from the beach, and then carried to a dump 
established in sand dunes about a mile from the 
water. One DUKW was inadvertently loaded above 
rated capacity to about 8,000 pounds but seemed to 
manage just as well as the others, which averaged 
about 5,000 pounds of cargo. Unloading of small 
packages at the dump was done by hand, while im¬ 
provised A-frames were used for large packages. 

A special tactical demonstration was devoted to 
the landing of a 105-mm gun battery with four 
DUKWs. The battery was taken through a 4- to 
5-foot surf (the highest available). The guns were 
unloaded with the A-frame, towed by the DUKWs 
across dunes not traversable by the standard prime 
mover, moved into battery, and there fired (Figures 
94 to 96). Unloading time without rehearsal was 
about 2 minutes for each gun. 

At the end of the demonstration, the DUKWs were 
turned over to the observers to drive and test in any 
manner they desired. 

Following the demonstration and critique, the 
Assistant Chief of Staff, WDGS, G-3, announced his 
decision to send small consignments of DUKWs into 
four theaters of operations. 

The demonstration, however, had been perhaps 
too successful. Because of the 30 days of rather drastic 
training with the LCT and because of the closest 
supervision during the demonstration, there had 
been no difficulty of any sort; thus the General Staff 
officers left Provincetown with the impression that 
the DUKW was a foolproof vehicle which could be 



Figure 93. At official Provincetown demonstration, 
DUKW operates through moderate surf with waves rang¬ 
ing up to 6 feet in height. 










DEMONSTRATIONS 


57 



Figure 94. DUKW brings 105-mm howitzer ashore in Provincetown demonstration. December 1942. 



Figure 95. DUKW takes role of prime mover to haul howitzer over Provincetown sand dunes. 



Figure 96. 105-mm howitzer unloaded from one DUKW with aid of A-frame on another is hauled into battery 
position. 


m^llAL r 


























58 


THE DUKVV: ITS DEVELOPMENT 



Figure 97. LCVs bringing cargo ashore in tests off Fort Story, Virginia. 



Figure 98. With LCV run as close as possible to beach, men wade into icy water to remove cargo. 



Figure 99. Men carry cargo from I.CV to waiting bulldozer and sled. 



Figure 100. Last stage in LCV cargo-landing routine. Men lift cargo on to standard land truck. (In Fort Story demon¬ 
stration, LCVs landed only about 30 tons in 90 minutes.) 




























DEMONSTRATIONS 


59 


operated in heavy surf by any troops with very little 
training. This undoubtedly was a factor in the fail¬ 
ure of the War Department to agree at once to the 
necessity for rigorous training of properly selected 
personnel, under competent military supervision. 

3 - 7 - 3 The Fort Story Demonstration 

Immediately after the Provincetown demonstra¬ 
tion and because of the interest of officers of Am¬ 
phibious Forces, Atlantic Fleet [AFAF] who had at¬ 
tended, the second major demonstration got under 
way at Fort Story, Virginia, culminating in a large- 
scale trial and competition with nonamphibious 
landing craft of comparable size. Again, the demon¬ 
stration was preceded by rigorous training and re¬ 
hearsal for a new set of inexperienced drivers. A 
method for unloading was developed by which cargo 
could be taken from a ship as fast as the ship’s gear 
could discharge it over the side. 

On January 3, 1943, in the presence of the Com¬ 
mander, AFAF, and his staff, ten DUKWs competed 
with ten LCVs in landing cargo from an AKA, with 
the DUKWs landing about 40 tons in 27 minutes and 
the LCVs about 30 tons in 90 minutes. Two days 
later in a repeat performance, the ten DUKWs 
landed 30 tons in 20 minutes, and the LCVs about 30 
tons in 90 minutes, while the ten LCVs which were 
reinforced with two 50-foot Higgins Tank Lighters 
brought in about 20 tons in 60 minutes. 

In these competitive runs, the LCVs ran as close as 
possible to the beach, where men had to wade into the 
water up to their hips to transfer the cargo through a 
small surf to the beach. Next a bulldozer dragged slecl- 
loads of cargo up to dry sand where it could finally be 


loaded on a truck (Figures 97 to 100). During the 
trials, one LCV was flooded and stalled and had to be 
rescued by a DUKW; half of the LCVs had consider¬ 
able difficulty in retracting from the beach after dis¬ 
charging their cargo; the 6x6 truck working with the 
LCVs had seven flat tires as a result of excessive tire 
deflation used to get across sand; and at the end, the 
commanding officer of the shore party reported that 
his men were freezing in the water and requested the 
aid of two DUKWs to get them back to quarters. 

In contrast, the DUKWs took cargo directly from 
the ship, carried it across the beach, and unloaded it 
at the dump by means of an improvised “hog trough’’ 
chute (Figures 101 and 102). With this system, one 
DUKW with a driver and a crew of four disgorged 
6,000 pounds of cargo in a minute and a half. 

One serious accident occurred when a Navy driver 
overloaded his DUKW with 9,000 pounds of cargo, 
putting most of it in the rear end of the cargo space, 
and then lay alongside the weather side of the AKA 
for 45 minutes in a 4- to 5-foot sea. He likewise failed 
to rig his tarpaulin and waited until the very last 
to use the emergency hand pump. At the end of the 
45 minutes, the motor stalled, the water gained fast, 
and the DUKW swamped in 60 feet of water. 

Following the demonstration and competition, the 
Commander, AFAF, requested COMINCH for 2,000 
DUKWs for the Sicilian invasion. Amphibious Sec¬ 
tion, COMINCH, turned down the request. 

Later, the DUKWs were used to demonstrate both 
wet and dry ferrying of tanks, half-tracks, trucks, and 
jeeps. In a similar experiment in conjunction with 
an LCV, the landing vessel unloaded the tank on a 
sand bar and the tank was then brought ashore by 
two DUKWs. In other operations, observers wit- 



Fic.urf. 101. In competitive demonstration at Fort Story, DUKW takes cargo from AKA standing offshore. 

















60 


THE DUKW: ITS DEVELOPMENT 



Figure 102. DUKWs bring cargo directly from ship through surf up to dump. Cargo is discharged by means of “hog 
trough” while DUKW is in motion. (In this demonstration, DUKWs landed about 30 tons in 20 minutes.) 


nessed methods for loading DUKWs down the No. 2 
hatch of Liberty ships (Figures 103 to 105), stowing 
them through the hatch of an LST, and suspending 
them from the davits of an AKA (Figure 106). 

3 7 4 The Guadalcanal Demonstration 

About 8 months after these demonstrations and 
after approximately 2,000 units had been produced, 


the relative value of the DUKW and the Water Buf¬ 
falo was questioned by naval authorities on the 
Pacific Coast. To settle this problem, two standard 
production DUKWs, selected at random, and a pair 
of Water Buffalo pilot models, one 4x4 and one 6x6, 
were dispatched to Guadalcanal. The DUKWs were 
in the charge of OSRI) personnel. 

From September 23 to 26, 1944, the four vehicles 
were used to unload cargo from ships standing off 
















DEMONSTRATIONS 


61 




Figure 104. Liberty ship jumbo boom lifting DUKW 
from water. 


- 


Figure 103. DUKW 7 alongside Liberty ship with DUKW' 
lifting sling being made fast. 




Figure 105. Stowage of DUKWs in Liberty ship, in hold 
and on deck. 


Figure 106. DUKW being lifted from water by AKA 
davits. 





































62 


THE DUKW: ITS DEVELOPMENT 


the beach at Guadalcanal. At the end of the first 2 
days, each DUKW had carried almost as much cargo 
as both Buffaloes together and had made more trips 
than either Buffalo. During the next 2 days, with the 
6x6 Buffalo laid up for repairs most of the time, each 
DUKW carried more than three times as much as the 
4x4. Similar results were obtained between Septem¬ 
ber 27 and 30 in comparable trials at Tulagi and in 
the Russells. 

The cargo consisted mostly of ammunition, ra¬ 
tions, and beer. 

The Navy report on the demonstration was favor¬ 
able to the DUKW but resulted in no Navy procure¬ 
ment. 

3 . 7.5 The Funafuti Demonstration 

In August 1943, CINCPAC was planning the as¬ 
sault on Tarawa and other coral atolls further west, 
and recjuested OSRD personnel to determine, by 
test on Funafuti and by observations during the oc¬ 
cupation of Nanomea, the extent—if any—to which 
DUKWs could climb out on coral reefs at various 
stages of the tide, on both the weather and lee sides 
of an atoll. 

OSRD urged that this test should include the LVT 
in order that the basis might be laid for a standard 


operating procedure for a coordinated assault using 
each of the two vehicles to best advantage. This was 
rejected. 

A consignment of 21 DUKWs was accordingly 
shipped from San Francisco to Funafuti, in the 
charge of OSRD personnel who serviced them en 
route. A detachment of Marine Corps personnel and 
a detachment of Army personnel trained in DUKWs 
at Fort Story were assigned to OSRD. 

First, this composite force was trained in Funafuti 
lagoon by unloading a Liberty ship over lagoon 
coral at all tides. Then, after OSRD personnel had 
dived under the surf with bundles of dynamite sticks 
in sandbags to blast a ramp in the seaward lip of the 
coral reef as a precautionary measure, it was found 
that DUKWs could land through the surf on the 
weather side of a coral reef of the Funafuti type 
without any such aid. (See Figure 107.) 

After 10 days of training, a group of 15 DUKWs 
with their crews was sent by LST to support the oc¬ 
cupation of Nanomea. This figure 8-shaped atoll is 
a continuous reef. Its outer shelf is several hundred 
yards in width, full of potholes, and exposed about 
18 inches at low tide. There is no entrance to either 
lagoon. On the weather side, the surf is heavy. On 
the lee side, the surf, deflected by each end of the 
atoll, strikes the coral shelf in two systems of waves 



Figure 107. Using 30-pound tire pressure, DUKW negotiates coral reef in tests at Funafuti. 


c> 






DEMONSTRATIONS 


63 


at right angles to each other and each at 45 degrees 
to the “beach.” A northerly current of about 1 knot 
runs parallel to the long axis of the figure eight. 
Great fingers of coral, separated by gullies deep 
enough to swallow DUKWs, plunge to the depths 
at the line where the confused seas break. 

From the point of view of making a landing, this 
reef is reputedly the worst in the Central Pacific, and 
OSRD personnel found it far more difficult than that 
at Tarawa, which they had visited before the war. 

Under these conditions, the Marine Corps drivers 
with 10 days of experience successfully landed on the 
Nanomea reef in the surf, being guided in a last- 
minute alteration of course by the difference in color 
between the dark water over the gullies and the pale 
green water over the coral fingers. Arriving at dusk, 
they discharged around the clock, taking combat 
stores from an LST lying offshore, running up a 
coral finger in the darkness by ranging in on two 
lanterns sited on the reef, and discharging directly 
to the dump. The stores were discharged by hog- 
trough over the side of the LST—a technique which 


was not successful with the jury rig available— and 
partly by entering and leaving the LST via its ramp. 

One DUKW was damaged by surging seas on the 
LST ramp. One fell in a gully. Each was back in op¬ 
eration within a few days. The others operated with¬ 
out incident. 

The operation made it clear that if relatively un¬ 
trained crews under close supervision could operate 
DUKWs across Nanomea reef in all tides, by night 
and by day, then a well-trained DUKW company 
coidd do the same far more easily at Tarawa, first 
bringing in batteries of 105’s and later supporting 
the assault with combat stores. A senior naval officer 
was present at the tests and concurred in the report 
which was sent at once to CINCPAC Headquarters. 
There the report was rejected. DUKWs were not 
used at Tarawa, either to land 105’s for enfilading 
fire or in logistic support of the assault. 0 

o For an account of a successful use of DUKWs to support the 
assault against stronger opposition and over more jagged coral 
than at Tarawa, see the description in Chapter 4 of the opera¬ 
tion against Peleliu. 








Loaded with Marines and combat supplies, a U. S. Army I)IJK\V is backed down the ramp of an LST. The scene: 
D-Day at Iwo Jima. 






64 










Chapter 4 

THE DUKW: ITS APPLICATIONS 


Summary 

UKWS a were first used operationally at Noumea in 
March 1943, a little less than 11 months after the 
Director of the Office of Scientific Research and De¬ 
velopment [OSRD] had launched the project, and 
thereafter went through the war without a major de¬ 
sign change, the basic design being considered satis¬ 
factory. The DUKW is one of few new weapons of its 
size with such a record. To eliminate those faults 
which, though minor, could cause a vehicle to fail in 
its missions, OSRD exerted the utmost pressure 
in getting necessary modifications into production. 
Some of the modifications requested by OSRD and 
approved by the War Department were, however, so 
long delayed in getting into production and so im¬ 
portant to efficient operation of a DUKW fleet that, 
despite the shortage of time, materials, and men in 
forward areas, they were improvised in the field. 

When the Army decided to start large-scale DUKW 
training, OSRD was already aware of many of the 
problems involved and was able to respond to the re¬ 
quest for assistance in setting up schools, writing 
technical publications, improving maintenance, and 
developing special operating techniques. OSRD per¬ 
sonnel were attached in a supervisory capacity to the 
early training schools in the United States and to re¬ 
training schools overseas. 

The work of OSRD in the indoctrination of higher 
commands with the potentialities of the DUKW be¬ 
gan with the sound film for the Joint New Weapons 
Committee of the Joint Chiefs of Staff, which out¬ 
lined a part of the potential role of an Allied DUKW 
fleet, ft was continued at a series of demonstrations 
for staff officers. In theaters of operations, cooperation 
of this sort was continued in conferences recjuested by 
the various theater commanders in the Mediterra¬ 
nean, European, and Pacific Theaters. 

Training aids, including photographic and written 
material, were prepared for the Armed Services at 
their request. Assistance was given in drafting operat¬ 
ing and other manuals; in theaters, special revised 


a Readers of this chapter should first read the Summary and 
the Introduction at the beginning of Chapter 3, which apply 
also to Chapter 4. 


editions of operating manuals were prepared by 
OSRD and published locally. 

Among the special logistical operating techniques 
developed by OSRD are stowage of various types of 
cargo in the DUKW, determination of the maximum 
permissible load for various conditions of sea and 
beach, DUKW mooring system, DUKW fleet control, 
operations with landing ships, evacuation of casual¬ 
ties, driving over coral, and underwater salvage. The 
most important tactical operating techniques in¬ 
clude the use of DUKWs with the 105-mm howitzer, 
use with the 25-pounder, and use with the 4.5-inch 
beach barrage rocket. In addition, OSRD repeatedly 
urged the exploitation of the strategic surprise ob¬ 
tainable by landing DUKWs on a coast line fronted 
by an “impossible” surf or by “impassable” reefs and 
beaches. 

Although one of the primary missions for which 
the DUKW was intended at the time of its design was 
to expedite the discharge of Lend-Lease cargoes in 
congested ports, OSRD worked with many officers 
and commands in finding new uses for the DUKW, 
including important tactical roles. In the end, OSRD, 
in close collaboration with theater forces, worked out 
a doctrine of a coordinated amphibious assault: 
DUKWs would be combined with LVTs to transport 
the assaidt troops, rockets, and 105-mm howitzers, the 
initial assault would be LVTs supported by rocket 
DUKWs, and subsequent covering fire wotdd be pro¬ 
vided by the 105’s landed by DUKWs; the whole 
force would get sea-lift in ramp landing ships. Com¬ 
bat supplies in support of the assault would be 
brought in by DUKWs. This doctrine was first used 
at Arawe in December 1943, later at Kwajalein, and 
finally became standard doctrine throughout the 
Pacific. 

OSRD made many attempts to insure that DUKW 
units overseas would be adequately supplied with 
spare parts, but these efforts were largely unsuccess¬ 
ful. Consequently, many DUKW companies relied 
on the cannibalization of other vehicles, especially 
DUKWs, and on the cooperation of Navy and Seabee 
machine shops for the fabrication of parts. 

In order to simplify DUKW maintenance, the 
early overelaborate maintenance instructions were 

L* 




G 


65 



THE DUKW: ITS APPLICATIONS 


66 


revised. These maintenance instructions were even¬ 
tually printed on dashboard plates. 

In the following pages, the principal military ap¬ 
plications of the DUKW are described, with particu¬ 
lar reference to various technical successes and fail¬ 
ures as they concerned the activities of OSRI). 

Total production amounted to approximately 
21,000 vehicles by August 1945, with a total of more 
than 27,000 authorized. 

As a result of these close connections maintained 
with the DUKW not only throughout its develop¬ 
mental phase but also throughout its application, 
OSRI) has arrived at certain conclusions and recom¬ 
mendations with respect to the problems encoun¬ 
tered. Among these recommendations is one for fur¬ 
ther study on the possibilities of a larger, 15-ton, z/ 4 - 
track amphibian which would supplement rather 
than replace the DUKW. Such an amphibian should 
be produced in both a combat model and a supply 
model. 

41 MODIFICATIONS 

As a result of continuous testing and observation 
in the United States and in theaters of operations, it 
was found that, although the basic design of the 
DUKW was sound, numerous minor changes were 
needed. OSRI) therefore exerted the greatest possible 
pressure to eliminate those faults which, however 
relatively minor in nature, could nevertheless make 
the difference between the success or failure of an 
operation. 

From the start of production until the end of the 
war, some 800 modifications were requested. 34 Most 
of them were initiated by the manufacturer to sim¬ 
plify shop assembly or to cope with a shortage of 
critical materials and were therefore not actually de¬ 
sign changes. A limited number were requested by 
the Army. The others were requested by OSRI) and 
were aimed at increasing the efficiency of the DUKW, 
expanding its versatility, and simplifying its mainte¬ 
nance. A representative list of some of the more im¬ 
portant of these design changes called for by OSRD 
is given in Table 1, with the date on which each 
change was requested, the date on which it was intro¬ 
duced into production, and the approximate delay 
involved. About two dozen of these important modi¬ 
fications had been requested by OSRD by the end of 
1943, and, although action on some of them was de¬ 
layed, the DUKWs available for the invasion of Nor¬ 


mandy in June 1944 were mechanically reliable, and 
2,000 of them operated around the clock continuously 
for 90 days, with practically no time for maintenance. 
Another dozen changes of this type were requested by 
OSRD in 1944, none in 1945. 

Table 2 gives a list of other changes which were re¬ 
quested by OSRD and approved by the Office of Chief 
of Ordnance, Detroit [OCOD], but which had not 
gone into production by the end of World War II. 

It should be clearly understood that practically all 
of the changes concerned the amphibious compo¬ 
nents and not the automotive components. I he latter 
had been incorporated into the conversion as well- 
proved, reliable units. 

On the whole, this would seem to have been a 
rather modest modification program, attended by re¬ 
grettable delays. The average time lag in getting the 
26 representative, important modifications into pro¬ 
duction was more than 10 months (Table 2). These 
modifications did not in general involve critical ma¬ 
terials or burdensome retooling problems. Some of 
the changes listed in Tables 1 and 2 were so vital to 
efficient DUKW operation that, despite the shortage 
of time, labor, and materials in the forward areas, 
they were made in the field. A few outstanding ex¬ 
amples of the work performed in the field to correct 
such production deficiencies are as follows: 

A-Frame Manufacture (see Table 1, MTER 2133). 
As mentioned in the section on accessory equipment 
in the previous chapter, production A-frames did not 
reach the theaters of operations in any considerable 
numbers; in fact, up to September 1944, there is no 
trace of a factory-made A-frame being used in the 
Mediterranean Theater, and it was necessary to im¬ 
provise these frames out of any materials available in 
the forward areas. 

Fuel Tank Drain Valve (see Table 1, MTER 2347). 
The large, packless fuel tank drain valve installed in 
fuel tanks having the sediment trap was installed in a 
bushing which was too lightly sweated into the tank. 
I he vibration during water operation caused a dan¬ 
gerous fuel leak around the bushing; consequently, 
the bushing had to be brazed or soldered to the tank 
or the heavy drain valve had to be removed and a 
lighter petcock installed. 

Sealing of Auxiliary Air Intake (see Table 1, 
MTER 2367). After 2 years of DUKW operations 
overseas, it was proved that this intake was not neces¬ 
sary to the cooling system; furthermore, since it was 
often inadvertently left partly open during water 


CONFIDENTIAL 







MODIFICATIONS 


67 



Table 1. Important Design Changes 

in DUKAV Production Models. 




Date 

Requested 

Date 

Put into 

Time 1 ag 

MTER* No. 

Description of Change 

by OSRD 

Production 

(Months) 

61 

Improved exhaust manifold 
(To reduce breakage in field) 

Jan.1943 

Aug. 1944 

19 

106 (a) 

Improved oil filter inlet 

(To reduce breakage in field) 

Oct. 1943 

Feb.1945 

16 

713 

Improved brake shoe springs 
(To reduce breakage in field) 

July 1943 

Jan.1944 

6 

2089 

Coamings raised 4 \/, inches 
(To increase effective freeboard) 

Jan.1943 

Mar. 1943 

2 

2133 

Manufactured A-frame 
(To permit lifting loads up to 
5,000 lb) 

Dec. 1942 

Sept. 1943 

9 

2141 

Heavier sloping windshield with 
side wings 

(To afford added protection in 
heavy surf) 

Feb.1943 

June 1943 

4 

2142 

Central tire-inflation system 
(To permit change in tire pres¬ 
sure while in motion, afloat, or 
ashore) 

July 1942 

Dec. 1943 

17 

2155 

Quick-action rudder control 
(To simplify water steering) 

Jan.1943 

Apr. 1943 

3 

2164 

Grease fittings on control lever 
bearings 

(To reduce tendency of bear¬ 
ings to freeze) 

Jan.1943 

June 1943 

5 

2166 

Two-speed marine propeller 
transfer case 

(To improve reverse operation 
when afloat) 

Jan.1943 

Aug. 1943 

7 

2170 

Bilge water hull drain valves 
(To drain hull after water 
operation) 

Jan. 1943 

June 1943 

5 

2193 

Improved V-strut bearing 
(To increase life of bearing) 

Feb.1943 

June 1943 

4 

2235 

Gould bilge pump system 

(To provide more dependable 
bilge pump) 

July 1943 

Dec. 1943 

5 

2347 

Fuel tank water trap 

(To facilitate removal of water 
from fuel system) 

Oct. 1943 

Dec. 1944 

14 

2360 

Locking flutes on rear wheel 
spacer studs 

(To facilitate removal of 
wheels) 

Oct. 1943 

Sept. 1944 

11 

2367 

Omit auxiliary air intake 

(To reduce probability of water 
getting on engine) 

Oct. 1943 

Oct. 1944 

12 

2369 

Stainless steel rudder cable 
(To increase life of cable) 

Oct. 1943 

Oct. 1944 

12 

2406 

Reduced tarpaulin bow height 
(To facilitate bow stowage in 
bow compartment) 

Oct. 1943 

Mar. 194 1 

5 

2426 

Copper fuel lines 

(To reduce clogging in fuel 
lines from rust) 

(Not recorded) 

Oct. 1944 



* Motor Transport Engineering Recommendations (CMC Symbols). 









68 


THE DUKW: ITS APPLICATIONS 


Table 1. ( Continued) 


MTER* No. 

Description of Change 

Date 

Requested 
by OSRD 

Date 

Put into 
Production 

r- ' 

Time Lag 
(Months) 

2514 

Install tachometer 

(To permit ready check on 
engine performance) 

Jan.1943 

June 1943 

5 

2527 

Install hand signal light 

(To facilitate visual commu¬ 
nication and serve as trouble- 
spotlight) 

Oct. 1943 

Oct. 1944 

12 

2561 

Lucite headlights 

(To reduce damage to head¬ 
lights) 

Jan.1944 

Jan.1945 

12 

2703 

Raised tire-inflation standpipes 
(To prevent standpipes jack¬ 
knifing over center) 

Jan.1944 

Jan.1945 

12 

2717 

Front brake hose protection 
(To protect hose from wire, etc.) 

July 1943 

Apr. 1945 

21 

2730 

Front brake hose protection 
(To reduce brake hose mortality 
and permit operation through 
water) 

Sept. 1943 

June 1945 

21 

2731 

Rear brake hose protection 
(To reduce brake hose mortality 
and permit operation through 
water) 

Sept. 1943 

May 1945 

20 

2768 

Correct setting of front axle stops 
(To reduce tendency to break 
shear pin or steering cable) 

Jan.1944 

Dec. 1944 

11 


* Motor Transport Engineering Recommendations (GMC Symbols). 


operation, much damage was caused to the engine. 
The intake was consequently welded shut and 
caulked all around. 

Steering Gear Adjustment to Prevent Shear Pin 
and Cable Failures (see Table 1, MTER 2768). Most 
failures were caused by faulty adjustment, which 
caused the rudder linkage at the stern to reach the 
end of its travel before the steering wheel rotation 
was stopped by the front axle turning stops. To pre¬ 
vent these failures, it was necessary to take four steps 
involving checks of the cable, rudder position, rud¬ 
der-control lever, and front wheel turning angle. 

Reinforcemettt of Coamings (see Table 2, MTER 
2813). The cargo coamings, particularly the rear 
coaming, were found inadequate to withstand the 
strains of handling such cargo as bombs and heavy 
lumber. The upper edge of the rear coaming was 
therefore reinforced with angle or channel iron and 
the corners with strap, and the side coamings rein¬ 
forced with strap. Any materials available were used, 
with many reinforcements improvised from barbed 
wire stakes. 


Use of Rust Preventive Thin Film (see Table 2). 
Excessive corrosion due to salt water, especially on 
the hull and the external brake mechanisms, was a 
constant problem. The application of Rust Preven¬ 
tive Thin Film (AXS 673) reduced this corrosion to a 
minimum. It was used on all outside surfaces, includ¬ 
ing the brake shoes and backing plates of new 
vehicles. 

Protective Grease on Brake Wheel Cylinders and 
Other Parts (see Table 2). Corrosion of the brake 
wheel cylinders, the three sealed ball bearings on the 
propeller drive shaft, and the winch drag brake¬ 
adjusting pin was minimized by the application of a 
mixture of one-third white lead and two-thirds water 
pump grease. 

Propeller Guard (see Table 2). This guard was in¬ 
stalled on DUKWs in the Pacific to minimize the 
chances of damaging the propeller and shaft during 
operations over coral and rock. The most satisfactory 
guard was made from 2i/£xi4-inch angle iron, but in 
many cases this material was not available. Some 
guards were made even with Japanese railroad iron. 
















MODIFICATIONS 


69 


Table 2. Important Changes Approved by OCOD but Not in Production by August 23, 1945. 


MTER* No. 

Description of Change 

Date Requested 
by OSRD 

2361 

Improved front springs 
(To reduce breakage) 

July 1943 


Move headlights 9 inches aft 
(To reduce damage) 

Apr. 1944 

2787 

Rubber-covered brake wheel cylinders 

(To increase life and eliminate need of complex grease 
protection) 

July 1944 


Use of Rust Preventive Thin Film (AXS 673) 

(To reduce corrosion and increase vehicle life) 

July 1944 


Protective grease on brake wheel cylinders 
(To reduce corrosion and increase life of parts) 

Oct. 1944 


Rustproof winch drag brake 

(To increase life and reduce possibility of dropping heavy 
loads ivhen A-framing) 

Mar. 1944 


Built-in hand bilge pump 

(To provide more dependable means of eliminating bilge 
water when engine or mechanical pump system not 
operating) 

Nov. 1943 

2812 

Clutch on air compressor and materially increased oil 
capacity 

(To decrease air compressor bearing failures) 

July 1944 


Propeller guard 

(To reduce damage to propeller shafts and propeller, par¬ 
ticularly in rough coral operation) 

July 1944 

2813 

Rear coaming reinforcement 

(To reduce damage and insure maximum effective free¬ 
board) 

Aug. 1944 


* Motor Transport Engineering Recommendations (CMC Symbols). 


Two important suggested changes which never re¬ 
ceived approval were still further increased hull free¬ 
board and a continuous rope fender built all around 
the hull. Each was suggested in January 1943, and 
each was rejected on the ground that it would slow 
down production. 

In addition, OSRD was sometimes able to arrange 
with the manufacturer for an advance shipment of 
kits for modifications about to go into production. 
This made it possible to bring up to date a group of 
DUKWs about to be shipped overseas. Thus, in early 
1943, before they were shipped to the Southwest 
Pacific, some DUKWs were modified at Fort Old, 
California, during the nights while they were being 
used for training by day; and in August 1943, the 
DUKWs shipped from San Francisco to Funafuti 
were partially modified and equipped with what 
spare parts could be obtained from the Stockton Ord¬ 
nance Depot over a week end. 

Even when the necessity for such field work is 
anticipated in the rear areas, the procurement of 
materials needed for making the modification and 


the time and labor required are major problems. Of¬ 
ten, however, vehicles were shipped direct from the 
mainland to a combat area; in such cases it was neces¬ 
sary to decide whether to put the vehicle into an oper¬ 
ation for which it was urgently needed, with the 
knowledge that it would require much additional 
maintenance work later, or to delay a much needed 
piece of equipment until it could be put into first- 
class operating condition. At Okinawa, for example, 
four amphibian truck companies arriving directly 
from the United States were not ready for operations 
until 2 weeks after the arrival of their DUKWs. How¬ 
ever, two companies arriving from Oahu, where they 
had been given time and assistance in modifying their 
vehicles (Figures 1 and 2), were in full operation 
within 24 hours of landing. 

In contemplating the amphibious conversion of a 
vehicle during wartime or any similar assignment, 
one might profitably consider the modifications de¬ 
scribed in this section and listed in detail elsewhere, 34 
the delays encountered with them, and the amount 
of field work necessitated by such delays. 









70 


THE DUkW: ITS APPLICATIONS 



Figure 1. Preparing vehicle for combat at DUKW 7 school 
on Oahu: DUKW brake wheel cylinders being coated 
with protective grease mixture. 


4.2 training and indoctrination 

During the early tests and demonstrations late in 
1942, OSRD personnel were required to provide 
Army and Navy crews with a certain amount of train¬ 
ing in the operation of DUKWs. Therefore, when the 
Army decided to start large-scale DUKW training, 
OSRD was already aware of many of the problems in¬ 
volved and was able to respond to the request for 
assistance in setting up schools, writing technical 
publications, and developing special techniques. 
This assistance was continued up to the end of the 
war. 

421 DUKW Schools 

Since the DUKW is a specialized weapon, special¬ 
ized training is necessary for its efficient operation: 
the DUKW operator must he not only an expert truck 
driver, with the ability to handle a large and cumber¬ 
some land vehicle, but also a coxswain and seaman, 
experienced in handling a craft less maneuverable 
than the normal boat; in addition, he must be able 
to cope with the very difficult problem of operating 
between land and water, where considerable skill is 
necessary to negotiate heavy surf, coral, soft sand, and 
beach wreckage. Finally, he must have a thorough 
grounding in hrst echelon maintenance, which, be¬ 
cause of the greater number of moving parts and their 
constant exposure to salt water, is more complex on 
the DUKW than on a land vehicle. 

The first Army personnel to receive DUKW train¬ 
ing were a small group from the Engineer Amphibian 



Figure 2. To minimize salt water corrosion, brake mecha¬ 
nisms and wheel backing plates are painted with zinc 
chromate and Rust Preventive Thin Film at Oahu 
DUKW school. 

Command at Camp Edwards, Massachusetts. When 
the Transportation Corps [ EC] school was started at 
Fort Story, Virginia, in January 1943, these men 
were used as instructors for several weeks until a suf¬ 
ficient number of TC officers and men were available 
to form a training cadre. At the request of the War 
Department, an OSRD adviser was permanently at¬ 
tached to the TC DUKW school until July 1943, 
when he was sent into active theaters to review and 
supervise DUKW operations and to organize re¬ 
fresher schools. After the first TC amphibian truck 
company was activated, training progressed until the 
facilities at Fort Story were no longer adequate. The 
school was moved in April 1943 to a site on the Isle of 
Palms, near Charleston, South Carolina, and con¬ 
tinued there until late in the year, when it was moved 
to Camp Gordon Johnston, near Garabelle, Florida. 
OSRD, when consulted, advised strongly against this 
move, for reasons which will appear. The training of 
amphibian truck companies continued at the Florida 
location until the spring of 1945, when activation of 
companies in the United States ceased. 

In addition to approximately 70 companies and 
several battalion headquarters trained at the TC 
school with the assistance and general supervision of 
OSRD personnel, other units were trained at a num¬ 
ber of points in the United States, including Fort 
Pierce, Florida; Fort Ord, California; Camp Ed¬ 
wards, Massachusetts; and Camp San Luis Obispo, 
California. Several General Motors schools were also 
established for the training of DUKW mechanics. 














TRAINING AND INDOCTRINATION 


71 


Thus, early in the program, training was given 
principally in the United States, with the major site 
at Camp Gordon Johnston on the Florida Gull Coast, 
where unfortunately the sand is firm and the water 
smooth. Fhe training cargo was unrealistic and the 
cargo-handling equipment was deficient. Battle- 
tested operating procedures were not taught. The 
curriculum did not take heed of the fact that the per¬ 
centage of 4's and 5’s (War Department classifica¬ 
tions) among the trainees was several times higher 
than the percentage of such groups in the Army as a 
whole. 

Because of these and other shortcomings listed be¬ 
low, OSRD found it possible to obtain support in the 
European Theater of Operations and later in the 
Pacific for the creation of special schools in the thea¬ 
ters for the retraining of DUKW crews and officers 
under OSRl) supervision. 

1. Since Camp Gordon Johnston was not located 
near a port of embarkation, it was not feasible to train 
each DUKW crew on its own vehicle. Consequently, 
the crews were trained on school equipment, with the 
result that vehicle maintenance was not spurred by 
any pride of possession. In the overseas schools, on the 
other hand, it was easy to teach first and second eche¬ 
lon maintenance to DUKW crews who “owned” their 
vehicles. 

2. Camp Gordon Johnston provided no opportu¬ 
nity to train DUKW drivers under conditions which 
were to become critical factors in actual assaults. 
There was no heavy surf like that at Tinian, no soft 
sand like the volcanic ash at I wo Jima, no coral like 
that at Okinawa. In the theaters, training conditions 
were selected to resemble those which would be en¬ 
countered when the unit went into operation. 

3. Since the overseas training schools worked in 
close liaison with the higher headquarters which later 
employed the units, more was known about their fu¬ 
ture assignments and, consequently, training was 
given when necessary for such special techniques as 
transporting 105-mm howitzers and crossing coral 
reefs or swift rivers. 

4. Overseas schools gave important assistance and 
advice to DUKW units on the procurement of special 
equipment and on the processing and modification of 
their vehicles. As mentioned above, there was much 
field work to be done on DUKWs after they had been 
shipped to the theaters of operations. 

5. Camp Gordon Johnston was located in the deep 
South. Although the first amphibian truck companies 


were made up of white personnel with either truck 
driving or stevedoring backgrounds, by the fall of 
1943 a change had been made to Negro enlisted men, 
though white officers were continued. There was a 
general lowering of the qualifications for DUKW 
operators; men with War Department classifications 
4 and 5 were taken from such widely divergent units 
as Air Corps security battalions, smoke generator 
companies, and antiaircraft battalions and put into 
amphibian truck companies. 

About half of these trainees were Negroes from the 
North. As was the case in other Southern camps, the 
morale of these men suffered from the necessity of 
conforming to the particular restrictions which they 
faced whenever they left camp. Such a situation 
would presumably have been less serious had the 
training camp been located in the North or on the 
West Coast. It actually was less serious, in fact, vir¬ 
tually nonexistent, in the overseas training camps, 
where the nearness of combat largely minimized 
many race prejudices. As a result of overseas training 
or retraining, Negro DUKW crews recovered their 
morale and acquitted themselves at least as well as 
white crews. In some cases they did better. 

In Europe, they received high praise for their work 
on the Normandy beaches; at Iwo Jima they made 
more tonnage under fire than did white companies; 
and in the heavy surf at Tinian they were unsur¬ 
passed even by the best white Marine Corps units. 

Nevertheless, there has been much discussion of 
the advisability of using such personnel as DUKW 
drivers. It has been held that operating the DUKW 
at sea, in high surf, over bad reefs, and on land, re¬ 
quires such a high degree of initiative and judgment 
that only men with special aptitudes and high per¬ 
sonnel ratings should be trained as DUKW crews. It 
is true that companies with a high percentage of per¬ 
sonnel of low I.Q. required a more thorough and a 
slower paced training, under closer leadership and 
supervision from their officers. But many of these 
Negro companies, retrained in theaters, have a per¬ 
formance record equal to that of the earlier com¬ 
panies composed of picked white men. In most cases, 
it was found that such a Negro company had officers 
of a very superior caliber, hardworking, enthusiastic 
about the DUKW, and sufficiently patient to cope 
with the multiplicity of problems inherent in the 
training of a group composed in large part of men in 
classifications 4 and 5. 

If future DUKW drivers were selected with an I.Q. 







THE DUKW: ITS APPLICATIONS 


72 


at least equal to the average for the Army, the need 
for the special slower training and for special officers 
could be eliminated, perhaps resulting in a more effi¬ 
cient over-all use of the nation’s manpower. 

Nothing in combat experience has indicated to 
OSRD observers that, with comparable officers and 
training, Negroes do not make as satisfactory DUKW 
crews as white personnel of equal I.Q. In some re¬ 
spects, they are probably more satisfactory. 

A particularly significant school was established at 
Fort Orel, California, at the request of the Command¬ 
ing General, Second Amphibian (later Engineer Spe¬ 
cial) Brigade, where OSRD personnel set up and car¬ 
ried out an intensive training course during the 10 
days prior to the sailing of the brigade. During these 
nights, the ordnance depot, under the supervision of 
GMC personnel, modified the 50 DUKWs and 
brought them up to date. 

The first overseas DUKW school was set up in 
North Africa in April 1943 to train units for the com¬ 
ing Sicilian operation. One officer from this school 
continued his work later in Sicily and in Italy, train¬ 
ing both American and British DUKW’ companies. 

The Chief, Combined Operations (British), had 
shown an early appreciation of the potential value of 
the DUKW’, and, at his request, OSRD personnel as¬ 
sisted in setting up a training program in May 1913. 
Their specific mission was to train a cadre of 50 offi¬ 
cers and noncommissioned officers who would carry 
on subsequent DUKW’ training. The first and princi¬ 
pal work of this instructor cadre was to be the train¬ 
ing of a 100-vehicle DUKW company which was to be 
used in the Sicilian landings in early July. 

The school was set up at Camp Dundonald, Scot¬ 
land, but training had to be started before the arrival 
of the first DUKW’s. Accordingly, some 2y 2 -ton trucks 
were borrowed and used to give as much training as 
possible before the arrival of the first DUKWs. Actu¬ 
ally, only two DUKW’s arrived during the period set 
for cadre training, and these arrived only 2 days be¬ 
fore the termination of this period. Since these ve¬ 
hicles were intended for combat in the very near 
future, additional difficulties were caused by the ne¬ 
cessity of checking and servicing the vehicles upon 
their arrival. 

OSRD personnel continued the work of training 
and indoctrination right up to the last moment, in¬ 
cluding some driver training given on the final trips 
out to the transports on which the DUKWs were to 
be loaded. Ship personnel were advised on the correct 


methods of handling DUKW s, including the carry¬ 
ing of a number of DUKWs in davits. The night be¬ 
fore the departure of the convoy, a dozen A-frames, 
invaluable later in unloading artillery from DUKW’s 
during the initial landings, were made under the 
supervision of OSRD personnel and delivered by the 
last DUKW to be loaded aboard. In view of all this 
pressure of time, much credit should be given to the 
DUKW crews, who performed well when they par¬ 
ticipated in the operation for which they had been 
trained. So great was their interest in their assign¬ 
ment that they took every available moment during 
the passage to the target to study written material on 
DUKW operations and maintenance. 

Later, when the Chief, Combined Operations, had 
become Supreme Allied Commander, Southeast Asia 
Command [SEAC], he requested OSRD to assist in 
setting up a DUKW’ school in India at Juhu, near 
Bombay, in December 1943. At this school, several 
Royal Army Service Corps [RASC] companies were 
trained for subsequent operations on the Arakan 
coast of Burma. Personnel of these units had already 
driven trucks on the rugged terrain of Iraq and Iran, 
and they developed into excellent DUKW f operators. 
An OSRD representative resided at this school for 
more than a month, and during that time introduced 
the DUKW mooring system, the transportation of 
artillery (principally the 25-pounder), the DUKW A- 
frame, the hog trough, the DUKW’ cargo pallet, and 
other techniques and equipment previously unfa¬ 
miliar to British DUKW’ units in India. DUKW 
maintenance procedures were modified to conform 
with the British Army “Daily Task” maintenance 
system. In addition, several demonstrations were 
staged to indoctrinate the Commanding General, 
33rd British Indian Corps, and other staff officers 
with DUKW capabilities. 

In the meantime, the future possibilities of the 
DUKW’ in Pacific operations had become apparent 
to some American staff officers. At their request, 
OSRD personnel went to the Ellice Islands in Sep¬ 
tember 1943 to train Marine Corps DUKW drivers 
for a special mission—the landing at Tarawa. On the 
basis of later operations, it appears that DUKWs 
would undoubtedly have been of prime value there 
in traversing the offshore reefs which proved to be 
such an obstacle to the conventional landing boats. 
Unfortunately, as noted below, the DUKW was not 
included in the Tarawa operation. 

In early March 1944, amphibian truck companies 









TRAINING AND INDOCTRINATION 


73 


were arriving in England preparatory lo the invasion 
of France. These companies were badly in need of 
training and other assistance in preparing for combat 
operations, and, accordingly, a TC DUKW school 
was started at Mumbles, South Wales, on the initia¬ 
tive of OSRD. The British Navy cooperated in mak¬ 
ing available a ship, complete with crew, for mooring 
and cargo-handling practice. This ship was used day 
and night in the intensive program necessary to train 
a large number of men in a short time. Fortunately, 
the Bristol Channel was rough during most of the 
training period, thus giving the students experience 
and confidence in a type of weather vastly different 
from the mild conditions at their school on the west 
coast of Florida. 

In the meantime, another school for British Army 
DUKW companies was training units at Towyn in 
West Wales. At the request of Headquarters, Com¬ 
bined Operations, this school was visited on several 
occasions by an OSRD representative in order that 
British DUKW 7 training could incorporate the latest 
operating and maintenance techniques that had been 
developed in other theaters. Also, at the request of 
Headquarters, 21st Army Group, visits for the indoc¬ 
trination of the commands were made to British 
DUKW 7 companies after their training and to the 
headquarters to which they were attached, at points 
where preinvasion exercises were being held. 

In addition to this work, an OSRD representative 
was also responsible for giving last-minute training to 
six Negro companies which had arrived from the 
United States only 10 days before D-Day. These com¬ 
panies were being staged near the port of Cardiff be¬ 
fore shipment for the French invasion. Several of 
their officers reported to the port command to which 
they were attached that almost the only DUKW 7 train¬ 
ing their men had received was at a DUKW 7 school in 
the United States, where they had been taken for 
rides, about 18 men to a vehicle, with an instructor at 
the wheel of the DUKW. 

One officer in the port command headquarters de¬ 
termined that these companies must receive more 
training, however brief, and requested aid from the 
OSRD man in charge of DUKW 7 training at the 
American DUKW 7 school in Wales. Since the work of 
this school was almost finished, attention was trans¬ 
ferred immediately to the six companies. Fortunately, 
they were already assembled on the dunes near Porth- 
cawl, on the Welsh coast, so the staging area was con¬ 
verted into a training area by the addition of a Dutch 


coasting vessel which was borrowed from the British 
Navy and anchored offshore. The weather was ex¬ 
tremely rough and the surf considerable, making it 
possible to give valuable experience to Negro drivers 
who had never before been at the wheel of a DUKW 7 . 
By virtue of round-the-clock training of the most in¬ 
tensive variety and the farsightedness and coopera¬ 
tion of the responsible TC officer, the men were pre¬ 
pared for their mission at least to some extent by the 
lime they were loaded onto their LSTs for Normandy. 

With the ever increasing demand for DUKWs in 
the Pacific and the complexity of the missions they 
were expected to perform there, the need for an “on- 
the-spot” school became apparent in the summer of 
1944. The island of Oahu, with its many facilities and 
its position as Headquarters, Pacific Ocean Areas 
[POA], was selected for the location and, with the aid 
of OSRD, the school was set up by the Army Port and 
Service Command at Waimanalo on the east coast of 
the island, an excellent site incorporating coral reefs, 
heavy surf, and soft sand. A pier was constructed with 
three cargo hatches and booms to simulate shipside 
conditions. Close liaison was maintained with the 
ordnance office, and valuable cooperation was re¬ 
ceived in the preparation of vehicles for combat and 
in the rapid correction of mechanical deficiencies 
that developed during training. This school con¬ 
tinued to operate up to the end of August 1945, pro¬ 
viding training not only for amphibian truck com¬ 
panies and battalion headquarters but also for many 
other DUKW 7 operating units from the Navy, Marine 
Corps, Army Air Force, Signal Corps, and Field Artil¬ 
lery (Figures 3 to 6). 

Fhe record of wartime DUKW training would sug¬ 
gest that if any future large-scale training of amphib¬ 
ian units should be given on the mainland, the pro¬ 
gram should be arranged so that the units are ready 
for combat when they are shipped. The military use 
of the DUKW provides outstanding support for the 
axiom that a piece of equipment, no matter how ex¬ 
cellent, will not perform satisfactorily unless its oper¬ 
ator is well trained. In every case in which DUKWs 
were issued to untrained personnel, the results were 
unfortunate. 

4-2 2 Training Aids 

Another phase of DUKW training and indoctrina¬ 
tion in which OSRD played a part was in the produc¬ 
tion of photographic training aids. Under OSRD 
direction, both still and motion pictures were made 


- CC fcN F 11. )RNTd AT - 





74 


THE DUKW: ITS APPLICATIONS 



Figure 3. DUKW drivers in training at Waimanalo school, Oahu, transporting 105-mm howitzer. A-frame DUKW 
leads way to beach so A-frame can be set up by time howitzer arrives on shore. 


of all the early tests and demonstrations in the United 
States, and by the beginning of 1943 there was suffi- 
cient material to make an album and a film. Copies of 
the album were distributed to interested General 
Staff Corps officers in Washington, to other officers 
elsewhere in the United States, and to the overseas 
headquarters of the theaters of operations. The film 
was made for the Joint Committee on New Weapons 
of the Joint Chiefs of Staff and was intended solely as 
a visual means of demonstrating the strategic poten¬ 
tialities of the DUKW to General Stair officers unable 
to witness actual field demonstrations. In addition, it 
proved to be a useful training aid in the orientation 
of driver students at the DUKW training schools. 


In April 1943, OSRD was requested by the War De¬ 
partment to make another film 1 ’ intended purely for 
training purposes. In addition to sequences showing 
various DUKW operations, such as mooring, winch¬ 
ing, and A-framing, this film used scale models to 
illustrate some of the mechanical details. 

Before this film was completed, the U. S. Army Sig¬ 
nal Corps went to the DUKW school at Charleston, 
South Carolina, in May 1943 to make Film Bulletin 
No. 26 on the DUKW, to be entitled “DUKW, the 


b This film was prepared by the Museum of Science and 
Industry, New York, N. Y., as subcontractor to Sparkman & 
Stephens, Inc., New York, N. Y., under OSRD contract OEMsr- 
154. 



Figure 4. DUKW drivers training in coral driving techniques at Waimanalo. Lookout man is stationed on bow to 
select best route through bad reefs. 










TRAINING AND INDOCTRINATION 


75 



Figure 5. DUKW driver brings his vehicle out of coral reef on to boulder-studded beach during training course at 
Wa imanalo. Instructor watches from beach as lookout on bow guides his driver. 


Seagoing Truck.” Although this was to be prelimi¬ 
nary to a full length training film, an attempt was 
made to put as much training value as possible into it. 
An OSRD representative was requested first to advise 
on its production and subsequently to provide the 
accompanying commentary. No full length training 
film was made but this film bulletin was used at 
DUKW schools in the United States and overseas. 

4 - 2 - 3 Publications 

The first official publication on the DU KW was the 
Operator’s Technical Manual, TM 9-802, 1 which was 
published in October 1942 and revised twice before 
the end of the war. This manual deals mainly with 
light and medium DUKW maintenance, and a copy 
is included in the auxiliary equipment issued on 
every DUKW. Several editions of a Service Parts 
Catalog for DUKWs, SNL G-501, were also issued, 3 
a copy being included with every vehicle. 

As soon as some of the early operating procedures 
were developed, OSRD produced a booklet of 
‘‘driver’s hints” in December 1942, with a revised edi¬ 
tion’ 1 issued in the spring of 1943. In the absence of 
any other operating manual for the DU KW, the Ord¬ 
nance Department waived regulations and early in 
1943 authorized the manufacturer to place a copy of 
the December edition in the map compartment of 
each vehicle. 

The urgent need for a more complete operator’s 
manual was soon evident, however, and in March 


1943, Field Manual 55-150, Amphibian Truck Com¬ 
pany, was written lor the Transportation Corps. 11 
Unfortunately, this publication was not issued until 
November and it was several months thereafter be¬ 
fore copies were distributed in the theaters. In the 
meantime, many new operating techniques had been 
developed, and many parts and controls on the 
DUKW itself had been changed. A new edition, 
therefore, was drafted in the spring of 1944, but again 
there was a regrettable delay, for it was not distrib- 



Figure 6. Cutaway model used at Oahu DUKW school to 
demonstrate many features not easily visible on ordinary 
production vehicle. 




76 


THE DUKYV: ITS APPLICATIONS 


uted overseas until early 1945, when it, too, had be¬ 
come out of date. 

Contrary to expectations, it was found that ur¬ 
gently needed publications could be produced over¬ 
seas with far less delay than in Washington, even in 
spite of the scarcity of printing facilities. On Oahu, 
the manual The DUKW—Its Operation and Uses 25 
was drafted by OSRD personnel for Headquarters, 
POA, in late September 1944; a month later, copies 
were being issued to DUKW companies as they com¬ 
menced training. In March 1945, a reprint 28 was pre¬ 
pared at Manila in a matter of days for the benefit of 
companies in the Philippines. A month later, it was 
decided to bring the manual up to date with the latest 
doctrines and with information on the current modi¬ 
fications, and in less than a month this new edition 32 
was in the field. 

Besides these operator’s manuals, numerous special 
instruction sheets prepared by OSRD were issued to 
the using Services in the field, generally in mimeo¬ 
graphed form. These dealt with such items as main¬ 
tenance, the mooring system, operations with LSTs 
and LSMs, stowage in ship’s davits, transportation of 
the 105-mm howitzer, use of the 4.5-inch beach bar¬ 
rage rocket, DUKW control, and coral operations. In 
addition, several technical bulletins summarizing the 
latest field modifications were issued by the Ordnance 
Department. 

424 Special Techniques 

As a result of its versatility, the DUKW was used by 
many arms of the Services on a variety of missions and 
under a variety of conditions. For such missions to be 
successful, careful study of the DUKW’s limitations 
and a full realization of its potentialities were neces¬ 
sary, and practical standard operating procedures 
had to be developed. Even for its primary function of 
unloading ships, special techniques needed to be 
evolved to enable the DUKW to yield the most satis¬ 
factory results. The most important of these standard 
operating procedures, as developed by OSRD in co¬ 
operation with the Armed Services, are described 
below. 

Logistical Techniques 

Cargo Stowage in DUKWs. In order that DUKWs 
will be operated in a seaworthy condition and that 
their chassis will not be subjected to undue strain 
when driven over difficult terrain, the amount and 


positioning of cargo must be carefully determined. 
Such a determination must embrace the following 
factors: type and bulk of cargo, sea and surf condi¬ 
tions, beach conditions, distance of land run, and ter¬ 
rain conditions. The maximum safe weight of cargo 
for a DUKW can vary anywhere between 2 and 5 
tons, depending upon these factors. The technique of 
DUKW loading should therefore be based on the ad¬ 
vice of personnel experienced in DUKW operations. 
This is properly one of the functions of DUKW con¬ 
trol described below. 

DUKW Mooring System. The DUKW mooring 
system was developed in the early days of field testing 
during late 1942 in order to enable a DUKW to moor 
at high speed alongside a ship at a fixed point and to 
remain steadily at that point while receiving its load. 

The system is based on the use of a single spring 
line leading astern to the deck of the ship. The power 
of the DUKW motor is used to hold the line taut after 
it is secured to the DUKW. The rudder is turned 
away from the ship, thereby holding the DUKW 
alongside and directly opposite the hatch to be un¬ 
loaded. 

The spring line is made of 3i/ 2 - to 414 -inch rope 
about 100 feet long, with the forward end of the line 
carrying a mooring hook which is engaged in the 
DUKW mooring eye. A messenger line leading to the 
deck of the ship directly above the mooring position 
is fastened to the spring line at the hook end. In order 
to allow the driver sufficient time to secure the hook, 
the lines are rigged so that the spring line has about 
10 feet of slack when it is not in use. 

Originally, the system called for rigging a heavy 
guest warp along the side of the ship, with the DUKW 
spring lines attached to it. Field experience, however, 
showed that the guest warp is not necessary and con¬ 
sequently the spring lines are led directly from on 
deck (Figure 7). Except for this one simplification, 
the original technique has remained unchanged since 
its inception and all DUKW personnel received train¬ 
ing in its use. Whenever possible, DUKW companies 
equipped themselves with lines in preparation for an 
operation, since it was found that, because of the un¬ 
familiarity of Navy and stevedoring personnel with 
the system, it was preferable for the DUKW units to 
provide and rig the lines themselves. The rigging of 
all five hatches of a Liberty ship in this manner takes 
two men less than 10 minutes. Navy approval was 
eventually granted, the system was included in the 
U. S. Navy Transport Doctrine published in 1944 by 





TRAINING AND INDOCTRINATION 


77 



Figure 7. DUKW using approved high-speed mooring sys¬ 
tem, which involves single stern spring line and power of 
motor. Second DUKW is waiting to move into position as 
soon as first DUKW is fully loaded and cast off from 
spring line. 

the Amphibious Forces, Pacific Fleet [AFPF], and rec¬ 
ognition became more general in each succeeding 
operation. In addition to the advantages already de¬ 
scribed, it was found that this system gives the most 
satisfactory results in heavy seas and that it can also 
be used to advantage by other types of landing craft, 
such as LCVPs and LCMs. 

DUKW Control. No matter how well-trained the 
drivers, the effectiveness of early DUKW operations 
was often greatly hampered by lack of understanding 
on the part of higher authorities. Improper use of the 
DUKWs usually resulted in wasting their potential 
carrying capacity, sometimes in causing maintenance 
to run unnecessarily high, and occasionally even in 
the total loss of the vehicles and their cargo. The ques¬ 
tions of which missions DUKWs should perform and 
which they should not, how much cargo they could 
safely carry, how many DUKWs are needed to keep 
a hatch operating at maximum capacity, and many 
other similar problems called for operational control 
by personnel experienced in DUKW work. 

Accordingly, OSRD developed and recommended 
a DUKW-control system which required the actual 
control work to be done by officers in the DUKW 
companies. Control points were set up at the beach, 
at the dump, on the ship, and in the parking area. 
Traffic was dispatched at a control center or com¬ 
mand post through which had to pass all requests for 


DUKW dispatching. In small operations, this control 
center could be run by the commanding officer of the 
DUKW company, but in an operation involving sev¬ 
eral companies, it was recommended that DUKW 
control be under a battalion headquarters. 

In all cases when a proper DUKW-control system 
was used, much higher tonnages of cargo were moved. 
Use of such a system meant that DUKWs would not 
be assigned to missions for which they are not suited 
and that their amphibious qualities would not be 
squandered in long land hauls. At the same time it 
provided higher authority with accurate information 
whenever necessary on DUKW performance and dis¬ 
position. 

Operations with Landing Ships. In the later stages 
of the war, landing ships, such as the LST and LSM, 
became increasingly important in transporting am¬ 
phibians to the scene of their assault missions. While 
it would have been imprudent for the Navy to bring 
its larger transports close to enemy-defended beaches, 
it appeared that these more expendable landing ships 
could approach within a few miles, where LVTs and 
DUKWs with artillery, assault troops, and other high 
priority loads could be easily and speedily discharged 
into the sea. 

As with many other techniques involving DUKWs, 
however, some difficulties were encountered, first, in 
convincing the using Services of the practicability of 
this operation and, second, in instituting the proper 
indoctrination. Even after this technique was 
adopted, several serious mistakes were made. When 
the pads recommended for the lower corners of the 
ramp curbs were not used on the LSTs and LSMs, 
DUKW' hulls were often pierced; DUKWs were in¬ 
correctly loaded on stern first (Figure 8) and propeller 
guards and pintle hooks were consequently damaged 
on the ramp as the DUKWs drove out bow first; be¬ 
cause of overloading, several DUKWs were sunk as 
they descended the steep ramp into a rough sea. 

Frequent demonstrations were staged to prevent or 
minimize these accidents and literature was distrib¬ 
uted as freely as possible. Operations with landing 
ships were incorporated by OSRD into DUKW train¬ 
ing programs, not only for the benefit of DUKW 
crews but for Navy and Coast Guard personnel as 
well. Eventually, as in the case of the DUKW moor¬ 
ing system, the standard operating procedure was in¬ 
cluded in the Navy Transport Doctrine of AFPF 
(Figure 9). 

Evacuation of Casualties. Special although quite 













78 


THE DUKW: ITS APPLICATIONS 



Figure 8 . DUKW discharging from tank deck of LST 
into sea. This technique is incorrect. DUKW should lie 
loaded on bow first so that it will back off, thus avoiding 
the possibility of damaging pintle hook, propeller guard, 
or propeller. 

simple techniques were devised to use the DUKW for 
transporting wounded from field dressing station to 
hospital ship (Figures 10, 11, 12). With such a system, 
casualties do not have to be transferred at the water’s 


edge from land vehicle to landing boat—a move that, 
with bad surf or reef conditions, can be hazardous to 
a badly wounded man. Moreover, because of its ex¬ 
tremely low center of gravity, the DUKW is far more 
stable than a boat and consequently does not subject 
casualties to such violent motion in rough water. 

When LSTs are used for hospital work, DUKWs 
can drive up the ramp while the LS I is afloat. 1 he 
casualties can then be transferred to the sick bay di¬ 
rectly from the tank deck. 

Coral Driving. The development of a technique 
for driving over coral, one of the most important tech¬ 
niques used in DUKW operation, has been described 
in another chapter. 0 

Underwater Work. The DUKW proved useful in 
salvaging sunken supplies and equipment and in re¬ 
moving underwater obstacles from important chan¬ 
nels. T he DUKW air compressor will supply the air 
necessary for a diver, and an A-frame may be used to 
raise heavy loads to the surface. For shallow water, an 
adequate diving mask can be improvised from the 
standard service gas mask (with canister removed); 
for greater depths, however, a more elaborate helmet 
should generally be used. Weights for ballast may be 
secured to a belt which can be easily removed. If ex- 

v See Chapter 3 in this volume. 



Figure 9. DUKW loaded with 105-mm shells, leaving LST off Noemfoor Island. Offshore reefs obliged landing ships 
to remain afloat while they were discharged by DUKWs which drove up ramps onto tank decks. Having backed off, 
DUKW is about to turn and head for shore. This demonstrates correct system of discharging. (Compare with Figure 8, 
which shows DUKW being driven out bow first.) 


mi. 

























TRAINING ANI) INDOCTRINATION 


79 


ceptionally heavy loads, such as a vehicle, are to be 
raised, additional flotation can be obtained by lash¬ 
ing several DUKWs together. 

Tactical Techniques 

Transportation of the 105-mrn Howitzer. One of 
the most valuable tactical uses of the DUKW was the 
landing of the 105-nnn howitzer in the early phases of 
an assault. By this means, batteries could provide sup¬ 
porting fire to infantry troops many hours, if not days, 
before it cotdd be given by other means. This tech¬ 
nique was used in many actual operations and was 
adopted by the British for the 25-pounder, the British 
field artillery counterpart of the 105. It was in Pacific 
island warfare that the most important results of this 
method were obtained. There the surprise element 
was capitalized to its fullest extent by landing the 
artillery at any point on a coast fronted for many 
miles by coral reefs. 

Although the technique was developed and dem¬ 
onstrated under the supervision of OSR1) in Novem¬ 
ber 1942 and used in Sicily the following summer, a 
year passed before any interest in it was shown in the 
Pacific Theater. T hen, at Milne Bay in New Guinea, 
a Marine Corps artillery battalion was trained in the 
technique, and a full chess demonstration 19 was 
staged under the supervision of OSRD personnel 
(Figures 13 and 14). This resulted in a decision by the 
Marine Corps to use the DUKW together with the 
LVT, so that in a typical landing the assault troops 
would be landed by LVTs while the DUKWs would 
bring in the artillery pieces and subsequently keep 
them supplied with ammunition. 

Army amphibian truck companies, specially trained 
in the technique of handling howitzers, were there- 



Figure 10. Demonstration ot casualty evacuation by 
DUKW during demonstration for Surgeon General, POA, 
on Oahu. Bottom layer of six litters is complete, first litter 
of top layer is about to be passed up. Space is left for two 
attendants. 

fore attached to Marine artillery units for the assault 
phase of the operation (Figures 15 and 16) and, in ad¬ 
dition, Marine DUKW 7 companies were activated for 
each of the six divisions. At the time of Japan’s sur¬ 
render, several Marine Corps amphibian tractor bat¬ 
talions were in the process of being converted into 
DUKW battalions. 

According to this technique, whether the DUKWs 
are employed by the Marine Corps or the Army, it 
was recommended by OSRD that the vehicles serve 
with the field artillery battalions. At the port of em¬ 
barkation, they are preloaded with the howitzers and 
approximately 15 rounds of ammunition. Some of 
them—usually one in five—are equipped with A- 
frames for unloading the artillery after it has been 
landed. The normal gun crew accompanies its piece 
in the DUKW. When unloaded, the DUKW becomes 



Figure 11. Passing up litters for top layer on DUKW. 
Handles of top litters can either be lashed with line or 
secured by plywood litter racks which are provided on all 
later DUKW models. 



Figure 12. Top layer of six litters completes total of 12 
litter patients and 2 attendants on DUKW. To protect 
patients from sun and spray, tarpaulin and bows can be 
installed. 















80 


THE DUKW: ITS APF’LICATIONS 



Figure 13. During OSRD-ini dated demonstration at 
Milne Bay, New Guinea, U. S. Marine Corps artillery is 
unloaded from one DUKW by another DUKW equipped 
with A-frame. 



Figure 14. In OSRD-initiated demonstration, Milne Bay, 
New Guinea, 105-mm howitzer is lowered to ground after 
being lifted from another DUKW which has moved away 
and is waiting to tow piece into battery position. 


a temporary prime mover until the conventional 
prime mover can be landed. Observations under com¬ 
bat conditions showed that a well-trained team can 




Figure 15. 105-mm howitzer with combat wheels stowed 
in DUKW, during demonstration on Oahu. 


rig the A-frame, unload the piece, and hitch it to the 
DUKW pintle hook in less than 75 seconds. 

Rocket DUKW. Use of the DUKW as a source of 
amphibious beach barrage rocket fire power is de¬ 
scribed in a following chapter.' 1 This use was first pro¬ 
posed to the Commanding General, Second Engineer 
Amphibian (later Special) Brigade [ESB], at Fort 
Ord, California, in February 1943, and equipment 
developed in collaboration with Division 3 was sent 
out with him to New Guinea. The equipment was 
later supplemented by four completely redesigned 
120-rail, 4.5-inch rocket launcher installations 
equipped with motor-driven drum switches for con¬ 
trolled ripple fire. On arrival in New Guinea in Sep¬ 
tember 1943, OSRD personnel found that this officer 
had not yet been permitted to use this weapon. Rep¬ 
resentations were made and, although it was impos¬ 
sible because of transportation difficulties to move 
the rocket DUKWs from Oro Bay where they then 
were to Milne Bay in time for a formal demonstra¬ 
tion, they were nevertheless included in the demon¬ 
stration by token. When the troops putting on the 
demonstration were activated as a force for the land¬ 
ing at Arawe on December 15, two of the four rocket 
DUKWs provided close supporting barrage fire, in¬ 
troducing this type of supporting fire to the South¬ 
west Pacific [SOW ESPAC]. I hese four vehicles con¬ 
tinued to supply beach barrage fire until they were 
replaced by larger rocket landing craft. 

Operations in “Impossible” Conditions. OSRD re- 

d See Chapter 16 in this volume. 


EOT1AL 


G 



















MAINTENANCE 


81 


peatedly pointed out the part that DUKWs coidd 
play in achieving strategic surprise by landing at 
points where the presence of heavy surf, coral, or off¬ 
shore sand bars had led the enemy to believe these 
coasts secure from attack. Since DUKWs with well- 
trained operators could safely negotiate a surf as high 
as 15 feet and could cross jagged barrier reefs and 
multiple sand bars, it was evident that the greater 
portion of enemy-held coast lines lay exposed to the 
possibility of amphibious assault. 

This technique was never fully exploited, although 
it was used in part at some points on the coasts of 
Sicily and Normandy, at Tinian, and in the Ryukyus. 

Evolution of Amphibious Assault Doctrine. Begin¬ 
ning with an amphibious vehicle designed primarily 
to expedite the discharge of Lend-Lease cargoes in 
congested harbors, OSRD worked with many officers 
and commands in finding new uses for the DUKW, 
including important tactical roles, which later be¬ 
came paramount. Finally, in closest collaboration 
with theater forces, OSRD worked out a doctrine of 
a coordinated amphibious assault which had these 
features: 

1. ft did not require sea-lift by vulnerable AKAs 
and APAs but used hard-to-torpedo LSTs or other 
ramp landing ships. 

2. ft provided close fire support by rocket during 
the period immediately preceding and following the 
assault. 

3. It provided for mounting the frontal assault in 
LVTs, carrying 75’s and flame where necessary. 

4. It provided supporting fire by 105’s brought in 
by DUKW. 


5. ft was supported logistically in the assault phase 
by DUKWs. 

This doctrine was first proposed in a series of con¬ 
ferences called by the Commander-in-Chief, Pacific 
Fleet [CINCPAC] at Pearl Harbor in August 1943, 
when it was presented as being applicable to the im¬ 
pending assault on Tarawa. It was rejected by AFPF. 
It was first demonstrated at Milne Bay in November 
1943, where it was adopted by the Commander-in- 
Chief, SOWESPAC, who first used it at Arawe in 
December 1943. The use of DUKWs to transport 
105’s was adopted, probably independently, by the 
Seventh Division for the assault at Kwajalein. In the 
end, the general theory of this assault, modified by 
substituting larger rocket landing craft for the rocket 
DUKW, became standard throughout the Pacific. 
Various groups, presumably independently, worked 
out the same or a similar general doctrine. 

43 MAINTENANCE 

4 31 Spare Parts 

The efforts of OSRD to insure that DUKW units 
overseas would be adequately supplied with spare 
parts were largely unsuccessful. These efforts began 
in late 1942, when a proposed list of parts to be 
shipped with every vehicle was submitted to OCOD 
and to the manufacturer. This list received joint 
approval, but it was not until almost a year later 
that any spare parts began to be issued with DUKWs, 
and even then they represented only a small propor¬ 
tion of the items on the original list. While this initial 



Figure 16. Demonstration on Oahu to stair officers to show use of 
DUKWs in transporting 105-mm howitzers. When howitzer is low¬ 
ered to ground, it is hooked to pintle hook on stein of DUKW, 
which becomes prime mover. 













82 


THE DUKW: ITS APPLICATIONS 


issue was useful in that it included such minor items 
as gaskets and spark plugs, it contained few of the 
major items peculiar— i.e., “parts peculiar” —to the 
DUKW. 

In the meantime, satisfactory channels for procur¬ 
ing parts overseas were nonexistent. In fact, for some 
theaters such as the Mediterranean Theater of Op¬ 
erations [MTO] parts were never even shipped. In 
some other cases, parts were actually shipped to the 
theaters, but even then they tended to lose their 
identity in ordnance supply warehouses and dumps. 
OSRI) personnel made frequent anti strong recom¬ 
mendations to ordnance authorities in the United 
States that a study be made of a more satisfactory 
DUKW parts supply system. One suggested solution 
was to ship a 90-day supply of the major parts pecu¬ 
liar with every DUKW, a recommendation which 
was endorsed by every theater headquarters when¬ 
ever proposed. Up to the end of the war, however, 
there were many instances when DUKWs were dead- 
lined for weeks at a time for lack of parts. 

This condition led to some very unorthodox meth¬ 
ods of emergency parts procurement in the forward 
areas. Navy and Seabee personnel were most coopera¬ 
tive in providing the facilities of their machine shops 
for the fabrication of such marine parts as propellers, 
propeller shafts, bearings, and rudders. When such 
assistance was not available, land vehicles and Navy 
landing craft were cannibalized as much as possible; 
in some cases, parts for DUKWs were adapted from 
parts on British, Australian, and even Japanese 
trucks and landing craft. And, as a last resort, other 
DUKWs were cannibalized. It should be pointed 
out, however, that while the cannibalization of sur¬ 
veyed equipment can sometimes be justified on the 
grounds that it reduces demands on shipping, the 
cannibalization of serviceable equipment merely re¬ 
sults in the gradual extinction of the operating fleet. 

432 First and Second Echelon 

Maintenance 

Early field experience soon proved that the some¬ 
what overelaborate instructions originally issued for 
DUKW maintenance were not satisfactory, ft was 
learned that better results could be obtained when 
a driver or mechanic was asked to work with a check 
list of only the essential maintenance duties to be 
performed, rather than with a long list including 
many unimportant duties. 


Accordingly, simplified check lists were made up 
for daily driver maintenance, weekly maintenance, 
and monthly maintenance. These lists were distrib¬ 
uted to companies undergoing training overseas and 
even to units that had been in operation for some 
time. Favorable reactions were received from the 
company officers and men. 

Later, these maintenance instructions were ap¬ 
proved by OCOI) and printed on instruction plates 
which were installed on the dashboards of all 
DUKWs. 

In order to reduce mechanical failures due to the 
corrosive action of salt water as much as possible, 
many external parts of the DUKW required coating 
with protective materials. 

As pointed out in Section 4.1, this work should 
have been done in all cases on the mainland; actually, 
however, it was done in the field except in a few cases 
in which a responsible ordnance officer at a port of 
embarkation, convinced of the importance of this 
work, undertook to have it done before shipping ve¬ 
hicles to a theater of operations. Consequently, the 
waterproofing of corrodible parts became a vital func¬ 
tion of DUKW units overseas, and drivers were 
trained whenever possible in these duties as a part of 
their normal first and second echelon work. 

In cases in which OSRD was unable to indoctrinate 
DUKW units in this work, or in which time or mate¬ 
rials were not available, serious corrosion resulted, 
with a consequent later increase in heavy mainte¬ 
nance and spare parts requirements, and a reduction 
in the operating life of the vehicle. 

44 MILITARY USE 

4,41 General 

Approximately 90 per cent of all DUKW opera¬ 
tions were conducted by DUKW companies. The 
great majority of these units were amphibian truck 
companies of the LI. S. Army Transportation Corps. 

The Table of Organization [T/O] strength of 
such a company was first set at 178 enlisted men and 
6 officers, with a captain as commanding officer, but 
in May 1944 this was changed to 173 enlisted men 
and 7 officers. Each company was issued 50 DUKWs 
and was designed to operate on a round-the-clock 
basis, but in actual operations this organizational 
strength proved inadequate. It was found that for 
efficient round-the-clock operation, a theoretical 





MILITARY USE 


83 


strength of 4.2 men per DUKW is necessary. This 
would give an amphibian truck company a T/O 
strength of 210 men; at least 15 of these men instead 
of the 11 as now prescribed should have mechanic’s 
ratings. 

With good operating conditions, it was expected 
that a company could haul cargo at such a rate that 
a 10,000-ton Liberty ship would be completely dis¬ 
charged in 72 hours. In practice, however, principally 
because of delays at the dumps and also because of 
enemy action and other factors beyond die control 
of the DUKW company, such a rate was very rarely 
maintained over a period of more than a few hours. 

Beginning at Sicily in June 1943, some DUKW 
companies were organized informally around a bat¬ 
talion headquarters. Early in 1944, amphibian truck 
battalion headquarters were activated in the United 
States by the Transportation Corps and were in¬ 
valuable in large operations, not only for handling 
a large proportion of the administrative work of the 
companies but also for acting as a higher headquart¬ 
ers to control the DUKW operation and to keep the 
operational and maintenance records. A battalion 
headquarters consisted of 12 enlisted men and 4 
officers. 

Marine DUKW units, known as U. S. Marine 
Corps DUKW companies, had an organization some¬ 
what similar to that of the Army amphibian truck 
companies, but a larger number of mechanics was 
usually allowed, thus enabling maintenance rates in 
Marine companies to stay well within the prescribed 
figures. 

The British Army DUKW companies were formed 
from RASC general transport companies. These 
units were composed of men with qualifications far 
higher than were required by the U. S. Army for a 
similar unit. Every man was selected for his driving 
and mechanical abilities, and the driver mainte¬ 
nance duties in these British companies were far 
more exacting. Each company had a strength of 470 
men and was issued 120 DUKWs, together with 12 
more representing a 10 per cent overstrength. 

The remaining 10 per cent of DUKW operations 
not performed by DUKW companies were accounted 
for mostly by odd vehicles attached to divisions or 
operated by battalions with special missions to per¬ 
form. Only a few DUKWs were operated by the 
Seabees or other Navy personnel. 

It is well at this time to point out the disadvantages 
under which DUKWs operated when not in a 


DUKW company. In such cases, the operators usually 
had not received adequate training in either opera¬ 
tion or maintenance of the vehicle. They were likely 
to encounter unusual difficulties in the procurement 
of spare parts and special tools. Also, it generally 
happened in such cases that the DUKWs were as¬ 
signed to the unit without additional personnel and 
therefore the drivers were expected to maintain and 
operate their usual organizational vehicles in addi¬ 
tion to their DUKWs. Consequently, not only the 
DUKWs but all the vehicles in the unit suffered from 
lack of proper maintenance. 

The final argument against this method of operat¬ 
ing usually became evident at the completion of the 
mission for which the DUKWs were procured, when 
the unit naturally lost all interest in them. They were 
left unattended in the parking area or turned in to 
some ordnance company, where they speedily de¬ 
teriorated from salt water corrosion until they were 
no longer serviceable. Had an amphibian truck com¬ 
pany or platoon been attached to the using unit for 
the performance of the mission, the using unit would 
have been relieved of the responsibilities of DUKW 
maintenance and similar problems for which they 
were not equipped. Then, at the termination of the 
mission, the DUKWs—still with their regular drivers 
and mechanics—could have reverted to their normal 
cargo-handling missions. 

In concluding this general survey of DUKW 7 op¬ 
erations, it is important to examine the attitude and 
morale of the men in the DUKW companies and to 
determine what they thought of their assignment 
and how their interest and morale should be rated. 
To OSRD observers, it appeared that the great 
ma jority of the men preferred working with DUKWs 
to any other work which they might have been given. 
Consequently, their interest was all that could be de¬ 
manded and their morale remained high. This was 
particularly true once they were shipped overseas 
and were issued their own vehicles, in which they 
could take a personal pride. The system of issuing a 
vehicle to a driver and an assistant driver and of 
permitting no other men to operate their vehicle at 
any time should always be followed. It was far from 
unusual to see men painting and cleaning their 
DUKWs in time that was supposed to be their own. 

The very fact that many companies were made up 
of men with no special qualifications, as already 
pointed out, made them all the more proud and 
interested when they found themselves identified 





84 


THE DUKW: ITS APPLICATIONS 



Figure 17. Initial landings at Sicily were made under smooth sea conditions. 


with a weapon as important, versatile, and highly 
praised by the press as was the DUKW. 

Below are described some of the principal am¬ 
phibious operations in which DUKWs were used 
under OSRD supervision or cognizance. It will be 
noted that although the DUKW" was originally in¬ 
tended exclusively for a supply function, many 
varied missions were developed for this vehicle, and 
in the end it came to serve as a tactical weapon almost 
as frequently as a logistical one. 

4 4 2 Mediterranean Theater 

The initial contingent of DUKWs to arrive in the 
Mediterranean was a group of 55 sent to Arzeu, 
Algeria, in March 1943. With them came 4 officers 
and 100 enlisted men from the Fort Story DUKW 
school. Even before the vehicles were tested, an order 
from headquarters, who apparently did not realize 
the potential importance of these men as a DUKW 
cadre, sent the four officers to a replacement depot, 
and the enlisted men were distributed about to vari¬ 
ous units. Only a handful of trained drivers stayed 
with the 55 DUKWs. 

In the hands of completely unskilled personnel, 
who performed only a negligible amount of main¬ 
tenance, the DUKWs soon fell into a deplorable 
condition. At this point, through the representations 
of OSRD to the War Department General Staff 


[WDGS], G-4, a qualified DUKW officer arrived 
from the United States and a course was set up to 
train completely new men to handle the vehicles. 
Since only a small number of DUKWs were in op¬ 
eration and many of these were being used in con¬ 
nection with amphibious problems, it was impossible 
to impart very much actual information to the 
trainees. Yet these same men were immediately used 
as a training cadre to teach other new men—while 
the original well-trained men from Fort Story were on 
other details. 

In April, General George Patton visited Arzeu 
for a demonstration of the DUKWs and immediately 
req nested many more for the forthcoming Sicilian 
invasion. This necessitated more drivers. With the 
extremely limited facilities and inferior training 
cadre, the quality of the products of the Arzeu school 
fell still lower. 

At the end of May, the British Army in Africa was 
allocated a few DUKWs out of the original 55 and 
on these vehicles the American officer sent to Africa 
at OSRD urging trained two RASC general transport 
companies for DUKW operation. 

Sicilian Invasion 

In the Mediterranean, the DUKWs were first used 
operationally in the invasion of Sicily on July 10, 
1943. The British on the east coast had about 300 
vehicles, which were divided between two RASC 


COM 










MILITARY USE 


85 



Figure 18. DUKWs used during Sicily landings to bring fuel directly from ship to fighter planes on newly captured 
airfield at Cape Pachino. 


companies and a temporary group which left Scot¬ 
land, after only brief DUKW training under direc¬ 
tion of OSRD personnel, to come directly to the 
beaches of Sicily. The Americans used about 700 
DUKWs, all handled by three Quartermaster truck¬ 
ing battalions and by three engineer combat regi¬ 
ments. 

The original landing was conducted through surf 
so mild (Figure 17) that one DUKW managed to 
make a safe landing with a cargo of more than 7 
tons. Although the bulk of the vehicles carried 
stores, a few landed 57- and 105-nnn guns just after 
the assault. On the evening of D-Day, the weather 
turned bad and so much surf built up that for two 
full days it was impractical to use landing craft for 
cargoes. On these days, and on the third day, 90 per 
cent of all tonnage was DUKW-hauled. 

Partly because of the enforced delay in bringing 
land trucks ashore but mostly because the proper 
use of DUKWs was not then understood, cargo was 
hauled directly from ships to dumps located 15 miles 
back from the beach. In some cases, gasoline was 
transported by DUKW from ships directly to planes 
on newly captured air strips (Figure 18). A sub¬ 


stantial number of DUKWs were even appropriated 
by ranking officers to deliver supplies right up to 
front line troops and during one counterattack some 
20 vehicles were captured by the Germans. 

Practically no driver maintenance was performed 
during the first fortnight. This was due to lack of 
appreciation by responsible DUKW personnel of its 
importance and to the official policy that if the 
DUKWs “lasted for two weeks, they would have 
served their purpose,” and no more would be ex¬ 
pected of them. This lack had far-reaching effects 
from which the Mediterranean DUKW fleet never 
fully recovered. 

In addition to their normal function, the DUKWs 
performed a great variety of tasks, ranging from the 
salvage of landing boats to taxiing high-ranking 
officers and unloading landing craft by A-frame (Fig¬ 
ure 19). They were frequently used to tow land ve¬ 
hicles across soft sand. Some vehicles became so tied 
up in such “special work” that they did not revert 
to company control for 3 weeks, during which their 
amphibious capabilities were wasted. 

The British DUKWs had no trouble in landing 
and the surf conditions in the British sector remained 




















86 


THE DUKVV: ITS APPLICATIONS 



Figure 19. Unloading cargo at Sicily by means of DUKW A-frame. Since load is more than 3,000 pounds, counter¬ 
weight is used on bow of DUKAV to prevent its tipping. In case illustrated here, manpower is being used, but it is 
better to use 1,000 pounds of ammunition or other cargo, or to install brace under pintle hook on DUKW stern. 


mild. There the main problems were the utter lack 
of cooperation from the Navy and the vast amount 
of waste motion in trying to find cargo to haul. The 
need for efficient centralized control became so ap¬ 
parent that the first DUKW-control system was 
evolved then and there. As with the American 
DUKWs, many unusual uses were found for the 
British vehicles, the most interesting of which was 
in salvaging material from sunken ships. Many im¬ 
portant replacement supplies were raised at a time 
when they were otherwise unprocurable. 

The following points became evident from the 
Sicilian operation. 

1. The ignorance of the capabilities and limita¬ 
tions of the DUKWs exhibited by ranking officers 
of both Army and Navy caused a great loss both of 
tonnage hauled and of the vehicles themselves. 

2. Control of DUKWs was a complicated problem, 
and one which greatly affected their efficiency. Naval 
cooperation was very poor, and DUKWs were too 
often used for unprofitable work. 

3. Dumps were located too far inland, and DUKW 
efficiency was reduced by the resultant long road 
hauls. 

4. Tables of Organization and Equipment were 
hopelessly inadequate to provide the maintenance 
needed for operation around the clock. Four men 
were found to be about the right number to handle 
each DUKW", but this number was virtually never 
available. 

5. The over-all potential of the DUKW fleet was 
not more than 25 per cent realized. 

In spite of these points, however, the impressions 


made by DUKW performance were so favorable, par¬ 
ticularly when compared to the alternative means 
of supply by LCM or LCVP plus human chain, that 
the Supreme Allied Commander, MTO, reported to 
the Chief of Staff that the DUKW had been invalu¬ 
able, greatly facilitating the flow of supply over 
beaches, that on one beach it had been used as an 
assault craft, and that he could use many more. 

End Runs. In the later stages of the Sicilian cam¬ 
paign, both the British on the east coast and the 
Americans along the north shore used DUKWs in 
commando raids or end runs; 105-mm batteries were 
landed and set up (Figure 20), and demolition equip¬ 
ment and men were carried. It began to be appre¬ 
ciated that the DUKWs were superior to landing- 
craft in this work, where the speed of advance made 
it impossible to provide for adequate reconnais¬ 
sance of landing conditions. 

Messina Straits 

On September 3, 1943, the British 8th Army in¬ 
vaded the mainland of Europe across the Straits of 
Messina. The current in the Straits is the second 
fastest in European waters, and naval authorities 
insisted that the DUKWs could not navigate in the 
narrowest section where the current speed is greatest. 
A wider place was chosen which required a run of 7 
miles across water in a 2- to 3-knot current. At dawn 
of D-Day, the entire force of 300 British DUKWs took 
to the water and swam across; not one failed to make 
the far shore. In fact, eventually more than 12,000 in¬ 
dividual DUKW crossings were made without one 
failure. 















MILITARY USE 


87 


The initial loads carried were extremely varied, 
including practically everything smaller than 3^-ton 
vehicles that an Army uses. The execution of the 
DUKAV part of the invasion was perfect up to ar¬ 
rival on the far shore; reaching the dumps through 
narrow, congested streets was another matter, how¬ 
ever, and the size of the DUKW was responsible for 
serious traffic jams, ft was immediately apparent that 
special roads would have to be cut for use of DUKWs 
only, and this was done by bulldozer. 

Soon after the invasion was started, experiments 
determined that DUKWs could easily cross the fast¬ 
est currents in the Straits, but by that time the dumps 
were firmly established and no regular trips were 
made on the shorter run. 

After the 8th Army moved north, the DUKWs fol¬ 
lowed up and worked the ports of Vibo Valentia and 
Sapri. Two platoons which temporarily stayed be¬ 
hind at the Straits made probably the longest over¬ 
water mass trip ever accomplished in DUKWs. In 
order to catch up with their headquarters, and be¬ 
cause tires were a very critical item at that time, 72 
DUKWs traveled from Messina to Sapri by water, 
a 2-day, 150-mile trip. All DUKWs arrived under 
their own power. 

Salerno 

In the meantime, two U. S. DUKW battalions 
made the Salerno landing against very strong enemy 
opposition. Because of the lack of cover, a great 
many DUKWs were struck by shell fragments and 
direct fire but these vehicles were cannibalized to put 
others back on the road. 

The spare part situation up to this time was crit¬ 
ical, for not more than 10 per cent of needed supplies 
were available. The fact that so many vehicles were 
kept running was a triumph of ingenuity and very 
hard work. 

When Naples was captured in early October, the 
two U. S. DUKW battalions moved in and handled 
port work. An abortive attempt was made at this 
time to break in a Negro trucking battalion on 
DUKWs. 

Under pressure to build up DUKW strength for 
the forthcoming Anzio landing, practically all ve¬ 
hicles were withdrawn from use by December. The 
next 6 weeks of frantic work by ordnance exposed 
the terrible toll taken by the lack of maintenance 
during the previous summer. As fast as DUKWs were 
“rebuilt” and put into a pool, other previously re- 



Figure 20. Unloading 105-mm howitzer from DUKW by 
means of A-frame on another DUKW. 


paired DUKWs would be found inoperative. In fact, 
of 20 such DUKWs taken to Salerno for embarkation, 
16 were rejected by ordnance inspectors. 

At this juncture, in response to a request from G-3 
for a report on the amphibious logistics and tactics 
of Pacific DUKW operations, OSRD personnel ar¬ 
rived at Headquarters, Allied Forces [AFHQ], Al¬ 
giers. Targets of vehicle availability and of tonnage 
capacity were set. 

End Run. In the last week of December, a number 
of DUKWs participated in an end run around the 
mouth of the Garigliano River. This was quite suc¬ 
cessful until the last trip back, when many vehicles 
became mired in the shallow mud in the center of 
the river. Even after prodigious labor to free them, 
several were permanently lost. While it was well- 
known before that the DUKW was poor in mud, this 
was the first operational loss resulting from it in the 
MTO, and spurred studies to improve DUKW per¬ 
formance in mud (see Chapter 3, Section 3.6.1). 

Anzio 

The Anzio landing, which continued in full force 
for 4 months, started off with a complete showdown 
on the results of poor maintenance of the U. S. 
DUKWs. Working side by side with two U. S. DUKW 
battalions was one RASC company which used 
DUKWs of the same age and mileage; yet on D + 4, 
the British deadline was only 14 per cent, whereas 
the U. S. deadline stood at 55 per cent. It took the 
services of six ordnance companies, either in whole 
or in part, to improve this condition. 

The initial assaidt at Anzio on January 22, 1944, 
had been quite normal—guns, ammunition, rations, 









88 


THE DUKW: ITS APPLICATIONS 



Figure 21. DUKWs landing at Anzio. The beach exit, 
specially paved with landing mat sections, is rarely re¬ 
quired by DUKW unless beach is muddy. 

and fuel were carried (Figure 21). In the succeeding 
months, every and any type of cargo weighing up to 


4 tons was brought ashore in DUKWs. By this time 
the Germans were fully aware of the importance of 
DUKWs to the Allies and made special efforts to 
disable them. Their favorite method involved the 
use of antipersonnel bombs and shells, which were 
all too effective (Figure 22). One vehicle, however, 
remained in service after having received more than 
200 holes in its hull. 

Up to this time it can be said that the ftdl potenti¬ 
alities of DUKWs had never been utilized. Control 
was improving, but lack of cooperation from the 
Navy remained a large factor in producing poor ton¬ 
nage reports. In the spring of 1944, following repre¬ 
sentations by OSRD in Washington, a senior officer 
from the Army Service Forces [ASF] visited the MTO 
and made a study of amphibious work. His recom¬ 
mendations included the activation of TC amphib¬ 
ian truck companies which, with proper training, 
could produce the tonnages that were theoretically 
possible. 

On this basis, four TC amphibian truck companies 



Figure 22. Near miss on DUKWs ferrying supplies ashore at Anzio beachhead. 











MILITARY USE 


89 



Figure 23. DUKWs loaded with assault troops discharging from LCTs under easy conditions in southern France. 


were formed under the control of the 147th Quarter¬ 
master Battalion Headquarters. It should be ex¬ 
plained that each company of two battalions formed 
earlier had had a T/O of 110 men, but that a paper 
battalion of 120 men had been divided between these 
two so that each company actually had more than 170 
enlisted men. The 147th therefore had about the 
same number of men per company but far better 
maintenance facilities. On top of this, special au¬ 
thorization was received for additional equipment 
and the companies normally handled all repairs 
through third echelon. 

Southern France 

The invasion of southern France began on August 
15, 1944 (Figure 23). All DUKWs were handled by 
three battalions, since it had been found impractical 
to have small numbers in the hands of Engineer 
Corps regiments. Each battalion landed 100 extra 
“old" DUKWs. Of their basic 200 Table of Equip¬ 
ment [T/E] vehicles, 20 were also “old" and the re¬ 
mainder were just off the assembly line and equipped 
with the new controllable central tire-inflation sys¬ 
tem. A considerable number of 40-mm, 57-mm, and 
105-mm guns were landed, the latter so rigged that 
they could fire from inside the DUKW. One “suicide" 
DUKW was also included, prepared to blow itself up 
in order to breach a concrete sea wall in case other 
means failed. 

One-half of all T/E DUKWs were equipped with 
locally manufactured A-frames and raisers because 
it was felt that this was necessary for the rapid un¬ 


loading of artillery pieces. After the assaidt phase, 
25 per cent, or one company, of these DUKWs were 
detailed to work dumps in place of cranes, of which 
very few were available. Thus only three companies 
actually hauled cargo, while the fourth worked A- 
frames in loading and unloading all types of vehicles 
(Figure 24). 

With the three companies hauling cargo, 5,000 
tons per day, or 33 tons per DUKW per day, were 
easily handled when ships were available. Again, 
Navy cooperation was generally lacking and about 
30 per cent of all DUKW hours were unproductive. 

As the main Army moved north, the DUKWs went 
into Marseilles and worked the east end of the port. 
This was not a very profitable venture and for much 
the same reason as was found at Messina: the DUKWs 
tied up traffic throughout the city and the shore-to- 
dump time became fantastically high. Unfortunately, 
it was impossible to cut special DUKW routes 
through Marseilles. 



Figure 24. DUKW A-frame used to unload Signal Corps 
wire from causeway in southern France. 


















90 


THE DUKYV: ITS APPLICATIONS 


Considerable salvage work on sunken vehicles and 
supplies was performed after the initial assault on 
the southern coast and later at Marseilles, but other¬ 
wise the work performed was routine. 

The main features of DUKW operation at this 
period were: (1) the outstanding success of an in¬ 
tegrated DUKW' battalion in handling large amounts 
of cargo day in and day out; (2) the full-scale use of 
radio, which in a large measure made this integra¬ 
tion possible; and (3) the considerable use of DUKW 
A-frames to substitute for unavailable cranes. 

When the Army reached Epinal, it was felt that 
DUKWs should be available for possible river cross¬ 
ings, and the 147th came to Lyon to practice in the 
Rhone River. It was immediately apparent that the 
swift current and the uncertain bottom together 
made for conditions completely different from any 
which had been met before. At first, a cable crossing 
rig seemed to offer the only feasible solution, and all 
drivers were trained to use it. However, as more 
experiments were made and greater experience was 
gained, it became clear that free-lerrying was su¬ 
perior, in spite of the fact that drivers required very 
intensive training in this method. 

f’he two 7th Army DUKW 7 battalions were trained 
in this procedure preparatory to a proposed crossing 
of the Rhine. Two DUKWs actually applied it 
earlier in connection with a commando raid on De¬ 
cember 28 and thus became the first Allied vehicles 
to cross the Rhine. This crossing was made at a point 
9 miles north of Strasbourg. 

Certain other experiments were also conducted at 
this time, particularly on the use of DUKWs in mud 
and on the firing of 3-inch antitank guns without 
special harnesses. Mud had always been responsible 
for the major operational failures of the DUKW, and 
methods were sought to reduce them. A fairly elabo¬ 
rate technique was evolved, and with a metal 
“ladder” to facilitate climbing muddy banks, it was 
thought that a skilled driver could negotiate reason¬ 
ably bad terrain. The 3-inch antitank gun, mounted 
on the wide 105-mm carriage, is undoubtedly die 
heaviest piece fired from a DUKW. With the gun 
held in place by the winch cable and with no special 
rig other than wheel blocks, its use on the DUKW 
was found to be entirely feasible. During the first 
few rounds, the gun appeared to be more accurate 
in a DUKW than when in normal ground position— 
a phenomenon due to the absence of settling of its 
wheels. 


443 European Theater 

Normandy Coast 

The ability of the DUKW to move stores across 
stormy beaches was deliberately exploited for the 
first time by the planners of the Normandy invasion. 
The German General Staff, according to later re¬ 
ports by the Commander-in-Chief, Allied Expedi¬ 
tionary Forces, felt that the storm-lashed Normandy 
beaches provided no means adequate to support an 
offensive by several million men. Their judgment 
coincided with that expressed to Division 12 in 1942 
by representatives of the Allied High Command, who 
concluded that the Allied forces would have to use 
captured ports, ft appeared logical, therefore, that 
the Germans should base their strategy on a stubborn 
defense and subsequent demolition of Cherbourg 
and the other ports. The DUKW fleet was an es¬ 
sential element in the strategic surprise of the enemy 
and continued to support the advance to the Rhine 
in all weather. Representatives of Supreme Head¬ 
quarters, Allied Expeditionary Forces, later advised 
the Chief of Division 12 of NDRC that between June 
6 and September 1 the Allied DUKW fleet had 
carried across the beaches approximately 40 per cent 
of the total stores landed. 

In the invasion of Normandy, the first DUKWs 
landed on D-Day and by D + 60 approximately 2,000 
vehicles were operating on the Normandy coast. Of 
these, about 800 were operated by the British, serv¬ 
ing under the British 2nd Army on its sector of the 
coast. The others were operated by amphibian truck 
companies of the U. S. Army Transportation Corps. 
Six of these companies, manned by white enlisted 
men, had been in England for more than 6 months 
before D-Day. They were attached to the 1st, 5th, and 
6th ESB’s and were trained under the cognizance of 
General Daniel Noce, whose EAC Command at 
Camp Edwards, Massachusetts, had supplied the de¬ 
tachment for the Provincetown demonstration in 
December 1943. Fully cognizant of DUKW problems, 
General Noce met with OSRD personnel in London 
in January 1944 to review the various recent develop¬ 
ments in other theaters, and arranged that these six 
companies, while stationed on the coasts of Devon 
and Wales, should be given ample time to incor¬ 
porate these new developments in their training. 

Other companies, manned by Negroes, did not 
begin arriving until late in March 1944. They were 
not in condition to meet the tonnage figures guaran- 




MILITARY USE 


91 


teecl to the Staff Planners. It was necessary to create 
facilities, retrain the men, and prepare their equip¬ 
ment. This was done under OSRD supervision. 

The 1st ESB landed on Utah Beach, the 5th and 
6th on Omaha Beach (Figure 25). Their DUKWs 
were loaded with high priority engineer equipment 
and ammunition. Routes through the underwater 
obstacles and the beach mine fields were being cleared 
and marked to a limited extent, but the beaches were 
under heavy enemy fire and a number of DUKWs 
were hit by mortar fire. Some were damaged by land 
mines, but it is of interest to note that while the 
driver of a land truck is generally killed or at least 
suffers broken legs if his vehicle detonates a mine, a 
DUKW driver is rarely hurt, the front wheels and 
engine compartment apparently absorbing the full 
shock of the explosion. 

The first of the Negro companies arrived on the 
beach in LSTs arid LCTs on D + 3; others arrived 
later and were attached to port commands. 

In order to minimize the DUKW land runs, trans¬ 
fer points were set up in the dunes close to the 
beaches (Figure 26). Some of the transfer rigs were 
built of pipe frameworks with winches installed; 
others consisted of a high lift truck together with a 
special overhead lifting finger mounted on either a 
land truck or a wood platform. Later, cranes arrived 
and to some extent replaced these transfer rigs. 

While the firm sand of the beaches was ideal for 
the DUKWs, other operating conditions were not 
so favorable. In the first place, the ships widely used 
in the early phases were the relatively expendable 
North Sea two- or three-hatch coasters with an aver¬ 
age 700-ton capacity. These ships were important 
because their small size made them difficult targets 


and because their shoal draft enabled them to anchor 
close to shore, though they had a very violent roll in 
the generally rough English Channel waters. In com¬ 
parison with the usual large freighters, these coasters 
were not suited to efficient DUKW 7 operations. Many 
of them had heavy guardrails along each side, and 
these caused much damage to DUKW hulls and head¬ 
lights. 

Another source of difficulty in the first few days 
was the great amount of tactical smoke which was 
generated among the ships. This made it so difficult 
for DUKWs and other landing craft to find their way 
between ships and beaches that it was very soon dis¬ 
continued as being more trouble than it was worth. 

Sea conditions were bad most of the time. The 
prevailing wind was from the northwest, making it 
particularly bad at Omaha Beach, which was open to 
the north. The surf ran high at times, and tides oc¬ 
casionally ran as fast as 3 knots. Further trouble was 
caused by the great amount of wreckage and spilled 
cargo close to the shore. There was a high mortality 
in DUKW propellers and rudders until drivers were 
instructed to disengage their propellers and coast 
through the most congested water areas. 

The installation of the offshore breakwater of 
blockships at Arromanches, in the British sector, 
was of great value to British DUKW operations. 
From then on, these DUKWs were able to operate in 
relatively smooth water, and their maintenance 
troubles were considerably lessened. A similar break¬ 
water off the American beaches had been almost com¬ 
pletely destroyed on June 23 in the worst summer 
storm for 20 years. This meant that the U. S. Army 
DUKWs were obliged to continue operations in open 
sea conditions, which caused higher deadline rates. 










92 


THE DUKW: ITS APPLICATIONS 



Figure 26. Loaded DUKW's ashore at Omaha licaeh. 


Also, since the captured ports did not become usable 
as soon as had been planned, the additional load on 
the DUKW fleet was prolonged. Every available 
DUKW had to be used day and night, and first and 
second echelon maintenance was largely neglected. 

By the middle of September, most of the DUKWs 
operating in the United States sector were in very 
poor condition, this through no fault of the drivers. 
To aggravate the situation, spare parts were not 
available except in extremely limited quantities. The 
reason for this is not apparent: a large supply of 
spare parts had been accumulated in England in 
preparation for the Normandy operation, but if they 
did arrive in France, they did not find their way into 
the hands of the hard-pressed DUKW companies. 
Field improvisation of spare parts and cannibaliza¬ 
tion of vehicles unquestionably used up many 
DUKW hours that could have been better spent on 
operations. 

In spite of all the difficulties, however, the flow of 
supplies brought ashore—40 per cent by DUKW— 


was so great that these beaches continued to act the 
part of major ports into the late fall. These 2,000 
DUKWs are reported to have averaged 21 tons per 
DUKW per day, an astonishing record in the circum¬ 
stances. 

Channel Ports 

Cherbourg was captured on June 27, but for sever¬ 
al months its value as a port could not be exploited 
fully because of the heavy damage suffered by its 
facilities; nevertheless, it at least afforded a smooth 
water anchorage and it was an important railhead. 
Logically, one of the first projects at Cherbourg was 
the construction of a concrete ramp for DUKWs. Sev¬ 
eral DUKW companies were moved in as soon as pos¬ 
sible and the first ships were discharged by them. The 
DUKA Vs brought supplies directly from ship to rail¬ 
road freight car, where cranes transferred the loads. 

Later, this same system was used at Le Havre and 
other Channel ports which, because of damaged fa¬ 
cilities, could not discharge ships at dockside. 


J 3TA L 










MILITARY USE 


•j:i 



Figure 27. DUKWs used as land transportation for in¬ 
fantry troops on German road. 


River Crossings 

When port facilities were repaired and the fighting- 
fronts moved farther away, some of the DUKW com¬ 
panies were converted into truck companies. Others 
retained their DUKWs but were used to provide 
land transportation along the highways of France 
and the autobahnen of Germany (Figure 27). But 
even in the heart of Europe, the amphibious qualities 
of the DUKWs were still needed in the crossing of 
such great rivers as the Rhine (Figures 28 to 30) and 
the Danube (Figure 31). Several DUKW companies 
were used to transport troops and supplies across 
the Rhine; with the use of the correct river-crossing 
technique (operations in swift coastal currents had 
been stressed at the school at Mumbles), no serious 
troubles were encountered in spite of the swift cur¬ 
rent. In some cases. Army divisions used DUKWs as 
part of their standard transportation across lower 



Figure 28. DUKW loaded with infantry approaching 
enemy-held side of Rhine River at Oberwesel. 


Germany. Their technique consisted of bringing the 
assault troops up to a town by DUKW, deploying on 
foot to capture the town, and remounting on the far 
side to proceed to the next town. By this means, the 
difficulties presented by demolished bridges were 
greatly reduced. Crossing a river by DUKW was 
found to be an unquestionably better method than 
using Navy landing craft which had to be transported 
from many miles away along the narrow and already 
traffic-crowded European roads. 

444 Pacific Theaters 

Solomons 

The 451st TC Amphibian Truck Company, the 
first to be activated and trained at Fort Story, was 
also the first to arrive overseas. It reached New Cale¬ 
donia in March 1943 and was ordered by headquar- 


















94 


THE DUKW: ITS APPLICATIONS 



Figure 30. DUKWs must point well upstream when crossing swift current in Rhine River. 


ters there to demonstrate the possibilities of DUKWs 
for ship unloading. 

The performance was impressive. A Liberty ship 
lying a mile offshore in Noumea Harbor was dis¬ 
charged at a rate of 22 tons per hatch per hour (Fig¬ 


ure 32), as compared to the usual 6 or 7 tons per hatch 
per hour when barges were used. The company was 
sent on to Guadalcanal and for many months un¬ 
loaded approximately 90 per cent of the rations for 
more than 100,000 troops on the island (Figure 33). 



Figure 31. DUKW crossing Danube River at Donaustauf, Germany, after other means of crossing were destroyed. 


















MILITARY USE 


95 



Figure 32. First operational use of DUKWs in discharging a Liberty ship, Noumea Harbor, New Caledonia, March 
1913, 10 months after project was authorized by Director of OSRD. 


In spite of these early excellent results, however, 
the company’s efficiency deteriorated rapidly, partly 
because of a complete lack of DUKW spare parts but 
also because of the failure of higher headquarters to 
appreciate the unfortunate effects of reallocating 
trained drivers to other jobs, overloading the ve¬ 
hicles, failing to provide sufficient time for proper 
maintenance, and fever. In September and October 
1943, following visits by OSRD personnel to Noumea 
and to the Solomons, the nonmedical conditions were 
alleviated to a certain extent, but it was many months 
later before an effective quantity of spare parts ar¬ 
rived in this area. 

In the meantime, other companies arrived, one 
from Espiritu Santo in the New Hebrides, where it 
had been engaged in ship discharging, and several 
from the mainland. These companies went to the 


Russell Islands and to the New Georgia group, where 
they served to unload offshore shipping. In Novem¬ 
ber 1943, after they had been reorganized on Guadal¬ 
canal following visits by the OSRD group, these 
Solomons-based DUKW companies were given their 
first opportunity to participate in an assault opera¬ 
tion, the landings at Bougainville Island (Figure 34). 
These landings were made in Empress Augusta Bay, 
on beaches swept by a heavy surf. No serious diffi¬ 
culties were encountered, however, although many 
landing boats were swamped. The DUKWs were 
largely responsible for supplying the assault forces 
with ammunition and rations. 

New Guinea 

The first appearance of DUKWs in New Guinea 
provides a good example of the risk involved in issu- 



Figurk 33. DUKWs in operation at Lunga Beach, Guadalcanal. 















96 


THE DUKW: ITS APPLICATIONS 



Figure 34. DUKW landing on beach in Empress Augusta 
Bay, Bougainville, Solomon Islands. 


ing a new weapon to untrained troops with orders to 
test it and report on it. 

In July 1943, 25 DUKWs were delivered at Milne 
Bay and issued for trial to the forces discharging ships 
there. Unfortunately, these troops lacked small-boat 
experience and did not study the maintenance man¬ 
ual. In 2 weeks the DUKWs were grounded; the re¬ 
port to Headquarters, SOWESPAC, stated that they 
were unseaworthy, impractical, and more time was 
devoted to maintenance than to operation. 

Because of this report, when the first two trained 
DUKW companies arrived at Oro Bay, in New 
Guinea, in September, they too were grounded. 

In October, when OSRD personnel arrived at 
Headquarters, SOWESPAC, it was found that the 
several hundred DUKWs then in New Guinea were 
being used largely for long land runs, as a result of 
the Milne Bay report. 

The OSRD mission was requested by headquarters 
to analyze the amphibious logistics of northern New 
Guinea and to recommend steps for the full exploita¬ 
tion of the DUKW fleet. Such recommendations 16 
were made early in November to Commander-in- 
Chief, SOWESPAC, G-3, and were immediately acted 
upon. Nevertheless, neither this vigorous action nor 
the numerous demonstrations staged by the OSRD 
mission succeeded in fully overcoming the setback 
received at Milne Bay, as was determined later when 
OSRD personnel next saw this DUKW fleet in ac¬ 
tion, on Leyte in 1944. 

With the arrival of trained amphibian truck com¬ 
panies from the mainland, however, the potentiali¬ 
ties of DUKWs began to be realized to some extent, 
and from that time on they participated in amphibi¬ 


ous operations whenever available. 1 hey started at 
Milne Bay and Oro Bay, which were being built up 
as bases for future operations against Japanese-held 
New Guinea and New Britain. Next, with the cap¬ 
ture of Lae, a company was moved there to supply 
the new airfields at Lae and Nadzab with aviation 
gasoline. All gasoline destined for forward areas was 
brought in by Liberty ships in 55-gallon drums. 
Eighteen of these drums, totalling about 7,500 
pounds, made an ideal load for a DUKW, and with 
the usual shortage of cranes, DUKW A-frames were 
used at the dumps for unloading. 

As in the Solomons, many hours of DUKW opera¬ 
tion were lost because of spare parts shortages. So 
critical did this situation become that DUKW officers 
went as far as Brisbane in an effort to locate these 
missing items. There were no spare parts at Brisbane, 
either. After more strong recommendations were sent 
back to the United States, some parts eventually did 
arrive, but in the meantime many DUKWs had been 
cannibalized in order to keep others operating. 

DUKWs were also issued to the Australian Army 
in New Guinea, and one of its general transport 
companies used DUKA Vs to supply forces at Buna 
while another company worked at Lae. The men in 
these units were entirely self-taught. Later it was 
possible for OSRD to work with these companies and 
correct some of their operational faults in a relatively 
short time, since both officers and enlisted personnel 
were of exceptionally high caliber and had previously 
obtained moderately good results under easy operat¬ 
ing conditions. Subsequently, after the Military had 
been advised on the basis of a preliminary recon¬ 
naissance that the conditions were suitable for 
DUKW operation, these men used DUKWs success¬ 
fully in the Finschhafen landing. 

At the invasion of Arawe, New Britain, on De¬ 
cember 15, DUKWs were used not only for supply 
work but to give supporting fire. Several DUKWs 
from the 2nd ESB were equipped with launchers for 
the 4.5-inch beach barrage rocket, e and although this 
fire power could have been afforded in part by other 
landing craft, the rocket DUKW could fire either on 
land or at sea and the results on the Japanese beach 
defenses were extremely effective. 

A request from Headquarters, SOWESPAC, for a 
total of 1,150 DUKWs was bringing more amphibian 
truck companies from the mainland, and they were 


e See Chapter 16 in this Volume. 
















MILITARY USE 


•)7 


playing an increasingly important part in amphibi¬ 
ous logistics. At Manus, Biak, Hollandia, and many 
other landings they served to supply the assault forces 
(Figure 35). In the assault on the Mapia Islands in 
November 1944, a battery of 105-mm howitzers was 
landed in DUKAVs and unloaded by A-frames. The 
guns were in action within 15 minutes from the time 
they were landed. 

Even after assault missions, DUKAVs were still 
needed at important points along the New Guinea 
coast for transportation duties until pier facilities 
could be constructed (Figure 36). When Headquar¬ 
ters, SOWESPAC, were moved to Hollandia, the 
continued service of several DUKW companies was 
necessary to build it up into a base for future assaults 
on Morotai and other islands to the northward and, 
eventually, on the Philippines. 

Ellice Islands 

As described on page 72, the first Marine Corps 
DUKW operations were in the Ellice Islands in Sep¬ 
tember 1943. After the men were trained, a group of 
21 DUKWs served to unload shipping in the lagoon 
at Funafuti atoll, which was being prepared as a base 
for coming assaults against the Gilberts and Mar¬ 
shalls. Here, for the first time, DUKWs operated over 
bad coral and proved that the findings made in the 
tests on the Florida Keys the previous February were 
correct: with skillful operation, DUKWs can be 
driven over bad coral reefs without appreciable dam¬ 
age or additional tire wear attributable to coral. 

From Funafuti, these DUKWs were sent to Nano- 
mea, to the northward, which was occupied without 
Japanese opposition except for bombing attacks. 



Figure 35. DUKW used by Signal Corps for laying under¬ 
water communications in Admiralty Islands. 


This small atoll has no passage into its lagoon, and 
its seaward reef is considered to be one of the worst 
in the Pacific. Yet, because of its proximity to the 
Japanese-held Gilberts, it was imperative that an air 
base be established there. LSTs were brought in as 
close as possible to the edge of the reef, and the 
DUKWs discharged them by driving up their ramps 
on to the tank deck, where they were hand-loaded 
and driven ashore over the reefs. 

Unfortunately, DUKWs were not used at Tarawa 
and in the other Gilbert Islands operations. Their 
use was rejected in spite of the DUKW operation at 
Nanomea, which was reported favorably to CINC- 



Figure 36. DUKW transporting troops on north coast ol New Guinea. Hard sand beaches along this coast seived as 
temporary roads. 















08 


THE DUKW: ITS APPLICATIONS 


PAC, Pearl Harbor, by the concurring Navy captain 
who had witnessed these tests and who recommended 
that the Navy include DUKWs in the plans for forth¬ 
coming landings. Many discerning Marine Corps 
officers, however, had become convinced of the future 
importance of the vehicles, and, in early 1944, Ma¬ 
rine Corps DUKW companies were organized and 
first used in the Marianas operations. 

Marshall Islands 

At Oahu, while preparing for the assault on Kwa- 
jalein atoll, the U.S. Army 7th Division took ad¬ 
vantage of the lessons of Tarawa and decided to 
capitalize on the valuable tactical use that could be 
made of DUKWs in landing 105-mm howitzers. Ac¬ 
cordingly, four provisional DUKW platoons were 
organized from division artillery personnel, and one 
platoon with its 15 vehicles and 3 A-frames was at¬ 
tached to each artillery battalion. The men in these 
platoons had been given no adequate training in 
DUKW 7 operation and maintenance, an omission 
which was later reflected in the condition of their 
vehicles after a few days of use. Nevertheless, the 
units landed their artillery at Kwajalein very effec¬ 
tively, having been discharged from LSTs which re¬ 
mained afloat. Although it was not necessary, as was 
shown in many subsequent operations, each DUKW 
had its side coamings recessed and its floor supports 
changed to accommodate the howitzer wheels. No 
modification is needed if the wheels are correctly 
chocked. 

After completion of their primary mission, the 
DUKWs were used to unload seven LSTs which 
served as floating supply depots. 27 The operations at 
Tarawa had already demonstrated that in atoll war¬ 
fare a more flexible system than the normal ship-to- 
shore operation is necessary. As in the Ellice Island 
operations, the DUKWs drove directly into the LSTs, 
and again the system proved very satisfactory. At 
Burton Island, one of the islets in the Kwajalein atoll, 
the beaches were under enemy fire for 36 hours and 
the shore party did not function until the island was 
secured. During that time, DUKWs carried combat 
supplies to forward dumps without casualties. 

DUKWS would have been even more useful in the 
Kwajalein operation, however, if they had belonged 
to a regular amphibian truck company attached to 
the division. In this way, they could have continued 
discharging ships after their primary missions were 
completed. As it w 7 as, the DUKWs were wasted to a 


great extent once the LSTs had been unloaded, for 
most of the ship unloading was done by a combined 
team of landing craft and tractors—a combination 
far less efficient than DUKWs. 

Marianas Islands 

The Marianas campaign affords another example 
of successful DUKW performance on very rough 
coral reefs. Except for Tanapag Harbor, a few unim¬ 
portant sections of coast line on Saipan, and two very 
small beaches on I inian, the islands are surrounded 
by barrier reefs. 

In these operations were two Marine DUKW 
companies and one Army company, the 477th Negro- 
manned unit which later gained additional distinc¬ 
tion in the assault on the Kcrama Islands. The 
Marine drivers had had no previous experience with 
DUKWs and only a minimum of training, but the 
Army unit, which was attached to the 5th Amphibi¬ 
ous Corps Artillery, had received extensive training 
on Oahu and was in excellent operating condition. 
The DUKWs were transported in LSTs to their lines 
of departure and on June 15, 1944, went ashore be¬ 
hind the assault waves of Amtanks and Amtracs. The 
first DUKW waves were used to bring in troops, then 
ammunition, and eventually rations and medical 
supplies. The depths were too great to permit the 
shipping to anchor offshore, and DUKWs were often 
obliged to search for their ship as it was shifted by 
the currents. T his made mooring alongside very 
difficult, especially since the ground swells were 
heavy. 

A great many casualties were brought out from 
shore by DUKWs. Their land ability was found to 
be good and another mission was found for them as 
prime movers for 155-mm howitzers over steep and 
difficult terrain. Eventually, when the island was 
secured, DUKWs were used to discharge some of the 
shipping in the relatively smooth waters of Tanapag 
Harbor. In the meantime, Marine Corps DUKWs 
under the 3rd Division participated in the landings 
on Guam on July 21, 1944 (Figures 37 to 39). 

I hirty-nine days after the beginning of the assault 
on Saipan, the same DUKWs were used at Tinian 
(Figure 40). The night before the landings, they 
crossed the 7-mile channel from Saipan under their 
own power, some loaded with 105-mm howitzers and 
75-mm pack howitzers and some with ammunition. 
They anchored that night in the channel and awaited 
the dawn, which was heralded by a great artillery 







MILITARY USE 


1)9 



barrage from Saipan. The landing points were two 
very small beaches which indented the lava coast, 
one of them 65 yards wide, the other 130 yards. They 
were so narrow that to have used them for unloading 
landing craft to any great extent would have been 
dangerous, for a few broached boats coidd have 
blocked the beach (Figure 41). On the fourth day 
a distant typhoon caused heavy ground swells and 
nothing conld operate in the heavy surf except 
DUKWs, which continued to discharge ships and 
support the offensive without trouble. For several 
days, DUKWs and transport planes were the only 
supply lines open. This was the first occasion on 
which official Navy recognition was accorded to the 
DUKW’s surf ability. 

Shortly after the cessation of hostilities in the Ma¬ 


rianas, another outstanding example of the sea¬ 
worthiness of the I)UKW was afforded. A passing 
typhoon had built up a tremendous sea and a small 
freighter had been swept on to the offshore reef at 
Saipan. It hung there with not only spray but solid 
seas breaking over its decks and washing men into 
the sea. Some LCVPs were sent out but all returned 
immediately, except one which was swamped and 
another which was drifting out to sea with a drownecl- 
out engine. Two LYTs that attempted to put out 
were also swamped. A call was sent through to the 
477th Amphibian Truck Company for some DUKWs. 
There were so many volunteers from the company 
that the commanding officer was obliged to order 
many of his men to remain on shore. Besides the men 
from the LCVP, approximately 70 men from the 



Figure 38. DUKWs and LVTs bringing in assault troops at Guam. 














100 


THE DUKW: ITS APPLICATIONS 



Figure 39. DUKWs under lire on beach at Guam. 


wreck were picked up alive out of the water. One 
DUKW was swamped when it was caught in the cross 
seas close to the stern of the ship, but all its men, too, 
were saved. 

As in many other operations, spare parts were not 
available during the Marianas campaign in suffi¬ 
cient quantities to keep up with the demand, and a 
number of vehicles were cannibalized in consequence. 

Palau Islands 

The landing at Peleliu Island in the Palaus was 
one of the most difficult encountered by I)UKWs in 
Pacific island warfare. The island is surrounded by 
an extremely jagged coral reef several hundred yards 
wide (Figure 42) and on September 15, 1941, when 
the assaidt was made, typhoon weather caused heavy 
swells. In addition, Japanese beach defenses were 
strong and carefully concealed in the coral outcrop¬ 
pings. 

In anticipation of heavy' enemy small-arms fire, 





the two Charleston-trained Army amphibian trnck 
companies attached to the Marine Corps for the 
assault had piled sandbags around the front and 
sides of their drivers’ cabs. This precaution was an 
excellent one; unquestionably it saved lives, although 
nevertheless several DUKW men were killed and 
many wounded, mostly by machine gun and mortar 
fire. The reefs contributed to high casualty rates, for 
the DUKWs were obliged to traverse the worst coral 
areas at extremely low speeds, and many times 
DUKWs were hung up completely until they re¬ 
ceived tow chain assistance from another DUKW. 

Besides bringing in the majority of the assault 
supplies, the DUKWs at Peleliu performed valuable 
work in evacuating many wounded from field dress¬ 
ing stations, carrying them across reefs almost im¬ 
passable by any other means, and delivering them 
to hospital ships. 

This effective use of DUKWs over jagged coral 
during the assault phase against strongly defended 
positions appears to confirm the assurances given to 



Figure 10. DUKWs at Saipan loaded with 105-nun howitzers and gun crews for invasion of Tinian Island. 












MILITARY USE 


101 



Figure 41. DUKWs and LVTs landing on one of two smali beaches on Tinian Island. Later, heavy surf forced LVTs 
to withdraw. 


the Navy in August 1943 that DUKAVs would prove 
satisfactory in supporting the assault on Tarawa. 

The original units at Peleliu were eventually rein¬ 
forced by another company which had participated 
in the landing at Angaur Island to the south on Sep¬ 
tember 17, 1944. Much more favorable conditions 
had existed at Angaur and the landing there was far 
less eventful. 

Philippines 

In the initial landings at Leyte on October 20, 
1944, DUKWs were used on a larger scale than in 
any previous Pacific operation. Thirteen Army am¬ 
phibian truck companies participated in the landings 
near Tacloban and Dulag. 29 > 31 Most DUKWs were 
transported in LSTs, but for the first time some were 
shipped in LSMs and LSVs, which afforded a very 
satisfactory means of transporting assault-loaded 
amphibians to the combat area. 

While sea and beach conditions ranged from mod¬ 
erate to good in the Leyte landings, the shore con¬ 
ditions were very poor and heavy rain turned the 
roads to deep mud. This held down tonnage figures 
which otherwise might have been very high, since 
in most cases the ships were able to anchor within a 
mile of the shore anti there was no need to contend 
with coral. Enemy air action interfered to some ex¬ 
tent, especially during the first 2 months; red alerts 
were frequent and of considerable duration, but 
DUKW losses were practically nil. 

For the first time, DUKWs and Weasels worked 
together in this operation as two links in the supply 
chain. To service the artillery batteries, which in 


many cases were located on steep, muddy hills, the 
DUKWs brought in the ammunition to a point at 
which mud halted them, and there their loads were 
transferred directly into Weasels, which completed 
the delivery. f 

As in most operations, there was a shortage of 
cranes and dumps became very congested. Once 
again, it was learned that DUKW operations are 
controlled by the speed at which they can be un¬ 
loaded on shore. If the dumps are slow, there is 
nothing to be gained by continuing to add DUKWs 
to the ship unloading cycle; additional DUKWs will 
only add further to shore congestion without unload¬ 
ing the ships any faster. 

DUKW 7 maintenance at Leyte was quite satisfac¬ 
tory, since operating hours were keyed to the under- 

f See Chapter 5 in this volume. 



Figure 42. Unloading of jeeps by DUKW A-frame from 
other DUKWs during Peleliu landing. Low tide exposes 
rugged coral reefs which DUKWs had to cross. 



















102 


THE DUKYV: ITS APPLICATIONS 



Figure 13. DUKWs landing supplies and troops at Puerto Princesa, Palauan Island, Philippines. 


strength T/O and the DUKWs were worked on a 
basis of two 12-hour shifts of 20 DUKWs from each 
company, with 10 DUKWs held out for regular main¬ 
tenance checks. This schedule was later moderated 
to three 8-hour shifts of 22 DUKWs per company— 
an unsatisfactory arrangement which, resulting in 
a breakdown in driver assignment, was later aban¬ 
doned. 

Some of the Leyte companies and others newly ar¬ 
rived from other islands or from the United States 
were used in the subsequent major landings in the 
Philippines, including Mindoro, the Visayan Islands, 
and Palawan (Figure 43). On January 9, 1945, three 
companies took part in the Lingayen Gulf landings 
in northwestern Luzon. The ground swells were 
quite heavy and the surf ran 6 to 8 feet high at times, 
but little trouble was encountered; slow-ups resulted 
mainly from conditions at the dump, as usual. 30 


When Manila Harbor was opened to United States 
shipping in early March, it was found that pier in¬ 
stallations were so damaged and so congested with 
sunken Japanese shipping that it was again necessary 
to use DUKWs to unload shipping (Figure 44). 
DUKW operations continued there until the end of 
hostilities. 

Iwo Jim a 

Three Army and two Marine Corps DUKW com¬ 
panies participated in the assatdt on Iwo Jima on 
February 19, 1945. Their primary mission was to 
land the 105-mm artillery battalions and to keep 
them supplied with ammunition. The three Army 
companies were made up of Negro enlisted men spe¬ 
cially trained at the DUKW school on Oahu for their 
mission and attached to Marine Corps artillery regi¬ 
ments for the assault phase of the operation. The 



Figure 44. Dl KWs operating in Manila Harbor, where damaged port installations made them necessary. 
























MILITARY USE 


103 



Figure 45. Two DUKWs, disabled and partially swamped at Two Jima, about to lie towed in by tractor. 


Marine DUKW companies had no operational ex¬ 
perience and almost no training, despite OSRD 
urging in Washington. 

The DUKWs, loaded with guns, ammunition, and 
gun crews, were discharged into the sea from LSTs at 
the line of departure some 4 miles out. Most of them 
went in only a few hours behind the assault waves of 
LVTs and landing boats, and the beaches were still 
under heavy mortar and machine gun fire from Mt. 
Suribachi. Information obtained before the opera¬ 
tion had indicated that all beaches would provide 
firm sand with easy traction for wheeled vehicles. 
This, however, was found to be completely inaccu¬ 
rate, for they were composed of a fine volcanic ash, 
so soft that it was extremely difficult to walk in it. 
Moreover, most of the beaches were so steep that the 
front wheels of the DUKW would bury before the 
rear wheels could obtain proper traction, whereupon 
the vehicle would be swung broadside on by the surf 


and swamped if it were not towed out without delay 
(Figure 45). Eventually, a few spots were located 
where, with tires deflated as low as 5 pounds, the 
DUKWs could climb out, and at other points tractors 
were assigned to pull each DUKW up the beach 
grade as it landed. 

Howitzers were unloaded by A-frame DUKWs and 
set up in battery position, and DUKWs then plied 
between the batteries and the ammunition-loaded 
LSTs to bring in 105-nim shells. The LSTs remained 
at sea for several days; because of the great depth of 
water, they could not anchor and hold their posi¬ 
tions, which made it extremely difficult for the 
DUKWs to locate them each time they made a trip 
from shore. 

DUKWs bringing the ammunition directly to the 
batteries were under mortar and small-arms fire most 
of the time while on shore, and consequently many 
of the hulls were punctured. Conditions were so crit- 


( ^NnPEN^ - TW T : - 











104 


THE DUKVV: ITS APPLICATIONS 


ical and the shore so crowded, however, that in the 
early phases of the operation it was necessary to 
send every 1)UK\V back out to sea, regardless of its 
seaworthiness. Several LS I s had been designated as 
DUKW repair ships; once aboard, the DUKW hulls 
could have been easily patched, but in many instances 
a badly leaking DUKW was not permitted to drive 
aboard at once and foundered while standing by. Of 
its 50 DUKWs, one company reported losing 15 
which could have been saved if taken aboard the 
LSTs immediately. 

Hie losses in DUKWs during the first 5 days—well 
over 50 per cent—were higher than in any other op¬ 
eration. Most of them were due to the causes de¬ 
scribed above, but other DUKWs were swamped in 
the heavy surf, damaged against LST ramps while 
attempting to enter a bad sea, or holed on sunken 
landing craft near the beach. Casualties among the 
DUKW drivers were surprisingly light; the com¬ 
panies averaged only 3 or 4 killed or missing and 
about 10 wounded. 

In spite of the combination of difficult operating 
conditions and high equipment losses, the DUKWs 
succeeded in bringing almost all of their howitzers 
to shore, unloading them with the utmost efficiency, 
and keeping them supplied with sufficient ammuni¬ 
tion to be one of the major factors in reducing the 
enemy garrison. 

The Army Negro drivers received high praise for 
their courage and ability from many Marine officers, 
including the Commanding General, Fleet Marine 
Forces. One driver ran out of fuel while searching for 
a bowser boat out at sea, but although landing craft 
offered several times to pick him off, he refused to 
abandon his DUKW and cargo, and drifted many 
miles to sea for 13 hours before a destroyer brought 
him in with his DUKW. When ship unloading 
started, the Army companies introduced the single 
spring line mooring system, which proved so success¬ 
ful in the heavy swells that the Marines also adopted 
it. 

Maintenance standards were also kept at a level 
far higher than that in many other landings con¬ 
ducted under easier operating conditions. This was 
due partly to the superior efforts of the maintenance 
sections in the DUKW companies, but also to the fact 
that, before loading at Oahu, they had received from 
the DUKW 7 school there valuable advice and assist¬ 
ance in procuring adequate supplies of spare parts. 

One result of the performance of the Army com¬ 


panies at Iwo Jima was an order from Fleet Marine 
Forces to the 4th and 5th Marine Divisions to send 
their DUKW companies to the Army-OSRD DUKW 
school on Oahu. 

At the opening of the garrison phase of the opera¬ 
tion, the three Army units were reinforced by an ad¬ 
ditional company, and all four reverted to the control 
of an Army amphibian truck battalion headquarters. 
Thereafter they served to unload Air Corps supplies 
and rations from offshore shipping. 

The Ryukyus 

The invasion of the Ryukyus opened on March 26, 
1945, with landings by the 77th Division in the Ke- 
rama Retto group. T he 477th Amphibian Truck 
Company, attached to this division for the landing 
and for supplying its artillery, was a Negro-manned 
unit which had already seen action in Saipan, Tinian, 
and the Philippines. The DUKWs went ashore on 
Geruma Shima 2 hours behind the assault waves and 
unloaded the artillery under enemy small-arms, ma¬ 
chine gun, and mortar fire, but without loss. 

Subsequently, the 477th moved on with the divi¬ 
sion artillery to Menna Shima, then to Ie Shima, and 
finally to Okinawa. On Ie Shima, extensive mine 
fields were encountered, and although other units 
suffered severely from personnel and vehicle losses, 
the DUKWs were fortunate in getting through with¬ 
out serious damage. 

On Okinawa, seven Army and three Marine Corps 
DUKW companies participated in the initial assaults 
on April 1, 1945. The units landed on the west coast 
near Yontan and Kadena airfields. Although there 
was no enemy opposition on the beaches, the coral 
conditions were extremely unfavorable, the outer 
edge of the reef being scored by deep fissures and its 
face pocked for several hundred yards with scour 
holes and pits where the islanders had cut out blocks 
for the construction of their tombs. These potholed 
reefs, over which the DUKWs drove day and night 
and at all stages of the tide except at high water, 
when they swam over (Figure 46), caused high mor¬ 
tality in front spring leaves, intermediate axle hous¬ 
ings, and other underbocly parts; on some days, one 
company would have as many as seven broken front 
springs. Accordingly, a new technique was success¬ 
fully developed for welding broken leaves. DUKWs 
in most of the companies were already fitted with the 
propeller guard described on page 68. The other 
companies, realizing the value of this modification 










MILITARY USE 


105 



in reducing damage to the propeller, propeller shaft, 
and strut bearing, installed it as soon as they could. 

In order to cut down the DUKW land runs as 
much as possible, transfer points were set up close to 
the operating beaches, and trucks were used for land 
hauls of 2 miles or more. On Okinawa, DUKWs were 
used in a truly combat role only when they brought 
the ammunition directly to the batteries during the 
artillery assault on the main Shuri-Naha lines. (For 
a noncombat role, see Figure 47.) 

The original Army companies, together with the 
3rd and 6th Marine DUKW companies, went under 
the control of two Army amphibian truck battalion 
headquarters on May 1, together with six more com¬ 
panies that arrived afterwards. Two of these new 
companies were from Oahu, two more had come 
directly from training in the United States, and the 
other two had come from the European Theater by 
way of the United States. It should be pointed out 
that the two companies with Oahu training were 
operating on a full scale within 24 hours of landing, 
while the other four required a minimum of 2 weeks 
to prepare and modify their vehicles. 

The need for DUKWs on Okinawa was vital. 33 
When the last organized Japanese resistance had 
been overcome in early July, the DUKW companies 
were required to work even harder, for the island 
was not only the site of 23 proposed airfields but was 
also being built up into a major base for the coming 
assault on the Japanese home islands. Naha Harbor, 
for which high hopes had been held as a port, was a 
disappointment, being too thickly filled with the 
wreckage of Japanese shipping to accommodate any¬ 
thing more than a few LCTs until October at the 
earliest. All the beaches were fronted by coral which 
dried out at half tide so that lighters could make only 
two round trips in 24 hours. Consequently, the serv¬ 


ices of DUKWs were essential to bring in the great 
majority of general cargo and Air Corps supplies. 

Each company was required to keep a minimum of 
35 DUKWs operating around the clock without let¬ 
up, week after week. This, together with the severe 
coral conditions and the fact that all but the units 
newly arrived from the mainland were under 
strength from the normal attrition of sickness, put 
such a strain on the companies that they were scarcely 
able to keep their maintenance up to an efficient level. 

At the end of June, however, higher headquarters 
were induced to order the Engineers to construct 
ground coral causeways to the edge of the reefs. 
Deadline rates decreased promptly, though a short¬ 
age of mechanics remained apparent. Eleven me¬ 
chanics, as prescribed in the T/O, are not enough, 
but by that time most companies were reduced to 
seven or eight. 

To assist in operations, a system of “hoppers” was 
put into effect. This system, first developed by OSRD 
at Funafuti in September 1943, consisted of having 
only one DUKW company man on a DUKW at one 
time. At shipside, the DUKW picked up a “hopper”— 
an additional man detailed for this work from the 



Figure 47. DUKWs used on Okinawa to evacuate civilian 
population. 


T^) ?v 7 EfDE4SrrtAl, 












106 


THE DUKW: ITS APPLICATIONS 



Figure 48. British DUKW landing on hard sand heach at Kyaukpyu, Ramree Island, Burma. 


Seabee or port unit operating the hatch—who assisted 
in mooring the DUKW and in placing the loads. 
After casting off the loaded DUKW from the mooring 
line, the hopper hopped to the next DUKW. In this 
way, even when a DUKW company was as much as 
10 per cent under strength, it could just manage 
round-the-clock operations. 

All the DUKW companies at Okinawa and one at 
Ie Shima continued to operate on a full-time basis up 
to the end of August, after which the flow of supplies 
to the island rapidly dwindled. Five of the companies 
were reconditioned to operate in Korea and to un¬ 
load supplies for the occupation troops there. Other 
companies continued to unload ships at various 
points in the Pacific after the end of the war, but on a 
very reduced scale. 

4,45 Southeast Asia Theater 

At the Quebec Conference in August 1943, the 
British requested a future issue of 8,000 DUKWs. Of 
these, a large proportion was intended for coming 
operations in Southeast Asia, although it was subse¬ 
quently realized that the great areas of mud and rice 
paddies on the Southeast Asia coasts made DUKWs 
unsuitable for large-scale use in amphibious work 
there. Eventually, only a few hundred were allocated 
to this theater. 

In late 1943, an amphibious assault on the port of 
Akyab on the Arakan coast of Burma was being 
planned. Two RASC DUKW companies were in 
training in India (see page 72) and a small fleet of 
LSTs and other landing ships was being prepared for 
the assault. At the Teheran Conference, however, it 
was decided that other theaters must be given a 
higher priority and consequently much of the equip¬ 
ment and supplies intended for Burma operations 


was diverted to the MTO and SOWESPAC. The ac¬ 
tual operation was therefore reduced in scale and had 
only the limited objective of establishing beachheads 
on sections of the Arakan coast above Akyab. These 
were to command the mouths of several rivers up 
which the Japanese were established. For this opera¬ 
tion, 25-pounder artillery was loaded into DUKWs, 
which in turn were loaded into the three remaining 
landing craft—one LSD and the only two LST(l)s 
still in existence. At the landing, the beaches were 
hard and unobstructed by coral, but inland the pres¬ 
ence of rice paddies and swamps made the terrain 
unsuitable for the use of anything but tracked am¬ 
phibians. After this section of the coast was secured, 
it was held for about a year, after which it was ex¬ 
panded by the landings at Akyab, Ramree Island 
(Figure 48), and Taungup. Several British DUKW 
companies participated in these assaults and in other 
operations (Figure 49) which led to the fall of Ran¬ 
goon in May 1945. 

4-5 PRODUCTION 

Beginning with an original order of 2,000 initiated 
late in June and received by General Motors Cor¬ 
poration on July 1, 1942, a total of 27,413 DUKWs 
was authorized for production. A total of 21,147 units 
had been built by August 15, 1945, when production 
stopped. 

46 CONCLUSIONS AND 

RECOMMENDATIONS 

In this review of the war performance of the 
DUKW, special attention has been given to the most 
important obstacles which occasionally blocked its 
efficient operation. An analysis of this review leads to 












CONCLUSIONS ANI) RECOMMENDATIONS 


107 



Figure 49. DUKWs ferrying supplies across river in Burma during British advance on Mandalay. 


certain conclusions and recommendations for more 
efficient solution ol similar amphibious problems in 
the future, whether they concern the DUKW or any 
related amphibious vehicle, either cargo-carrying or 
combat. 

4 - 61 Design 

Limitations of the DUKW 

While emphasizing the vital and varied missions 
the DUKW fulfilled, this review of its performance 
also discloses certain limitations and shortcomings 
which could be avoided in future designs. During 
wartime, it was very logically decided that all avail¬ 
able production facilities should be concentrated 
upon the DUKW; since it was a conversion design 
based upon a standard chassis and motor, it could be 
produced with maximum speed and in sufficient 
quantities to meet the urgent demands of the thea¬ 
ters. In peacetime, however, with time and develop¬ 
ment facilities available, full study should be given to 
the advantages offered by a larger amphibian de¬ 
signed from the ground up K — that is, with no existing 
standard land vehicle as a basis. 

It was apparent that, as a result of its physical char¬ 
acteristics, even the 1944 production DUKW was not 
a perfect all-purpose vehicle. Some of its more im¬ 
portant limitations are indicated as follows: 

1. Unsuitability for Many Cargoes. Because of the 


dimensions of its cargo compartment (82x149 inches), 
the DUKW cannot transport many types of cargo, 
particularly (a) 155-mm howitzers, (b) vehicles larger 
than the 3^-ton truck, (c) crated airplane motors, (d) 
pilings, and (e) other heavy lumber, building sec¬ 
tions, and similar structural material. 

At first glance, the fact that the DUKW is limited 
in the cargoes it can carry would not seem to be a very 
serious shortcoming. Landing craft and barges are 
generally available for handling loads unsuitable for 
DUKWs. But even in the garrison phase of an opera¬ 
tion, when convoy-laden ships must be discharged, 
serious losses of time occur with joint use of DUKWs 
and lighters. Although DUKWs may commence dis¬ 
charging a ship, they must be replaced by LCTs or 
other lighterage every time a load unsuitable for 
DUKWs—such as 2 i/ 9 -ton trucks or airplane motors— 
is uncovered in the hold. When this barge load has 
been discharged, the DUKWs, which meanwhile have 
been lying idle, are called back to continue opera¬ 
tions. Additional delays are involved in readjusting 
cargo booms and mooring lines. 

2. Small Capacity. By whatever means a ship is be¬ 
ing discharged, whether by amphibians or by lighter¬ 
age, time is lost from the moment one loaded craft is 
moved away until the next awaiting craft is moved in 
and moored alongside. With efficient and well-trained 
DUKW drivers, this delay can be cut to a matter of 
seconds. Nevertheless, it is estimated that the average 
time lost between DUKWs at shipside is . 81/9 minutes. 


k See Chapter 10 in this volume. 










108 


THE DUkW: ITS APPLICATIONS 


(While the cargo capacity of a DUKW ranges between 

2 and 5 tons, the average load is 3 tons; thus, for every 

3 tons ol cargo hauled, 3 i/ 2 minutes are spent in com¬ 
ing alongside and mooring.) This serves to demon¬ 
strate a very definite shortcoming resulting from the 
small cargo capacity of the DUKW. It should also be 
noted that this shortcoming has an effect, although to 
a lesser degree, at the shore unloading point, where 
additional time is lost while one DUKW moves off 
and another moves in under the cranes. 

3. Unloading Problems on Shore. There are sev¬ 
eral methods of unloading DUKWs when they reach 
their shore destination. One is the hand system, 
which involves a large dump crew and is slow and re- 
quires very hard work. The other methods call for 
some kind of lifting device, such as a crane or an A- 
frame, and consequently numerous delays occur be¬ 
cause (a) the unloading devices are not available at 
the dumps, (b) the unloading devices are undergoing 
repairs or maintenance, or (c) operators are not avail¬ 
able. Therefore, if it were possible to devise some 
efficient means of unloading amphibians without the 
use of lifting devices, operating efficiency would be 
greatly increased. 

4. Low Speed in Water. Since the DUKW is a con¬ 
version design based on the use of a standard land 
chassis, the wheel suspension, drive shafts, and differ¬ 
entials become wet appendages which must be housed 
to varying extents. All these appendages produce ex¬ 
tra drag and reduce water speed so that in a moderate 
head sea, for example, the DUKW' can rarely exceed 
5 mph. This low speed in water precludes the efficient 
use of DUKWs in discharging ships lying more than 
2 or 3 miles offshore, for the number of vehicles re¬ 
quired to keep the hatches operating continuously be¬ 
comes very great. 

Thus, in a typical DUKW operation, if a five-hatch 
ship is anchored 1 mile offshore, only 35 DUKWs are 
needed to unload her with maximum efficiency. In 
contrast, if the ship is obliged to anchor 5 miles off¬ 
shore, 95 DUKWs are required. 

5. Poor Performance on Mud. While the tires on 
the DUKW enable it to surpass the performance of 
almost any other wheeled vehicle on soft ground, 
it is still unsatisfactory in bad mud. Unless a mat¬ 
ting or causeway can be laid down in advance, 
DUKWs, or any other amphibian propelled by 
wheels instead of tracks, should not be used in an 
attempt to cross muddy rivers, swamps, rice paddies, 
or tidal estuaries. 


Proposed Improvements 

In the case of an amphibian designed from the 
ground up, some of the inherent shortcomings of the 
DUKW described above could be avoided. Any new 
amphibian design under consideration should there¬ 
fore incorporate the following characteristics: 

1. Larger Size. An amphibious cargo carrier signifi¬ 
cantly larger than the DUKW' would have a greater 
cargo capacity, which would permit three needed im¬ 
provements: 

(a) The amphibian could handle many types of 
loads that cannot be handled by DUKWs, such as 155- 
mm howitzers, trucks, light tanks, and large crates. 
Thus each time a heavy load is uncovered, no time 
would be wasted at a hatch while amphibians are re¬ 
placed by lighters. 

(b) By virtue of its greater cargo capacity, the ratio 
between the time taken by the amphibian in coming 
alongside the ship and the tonnage received by the 
amphibian would be decreased. With a 15-ton capac¬ 
ity amphibian, for example, only 3y 2 minutes would 
be lost for every 15 tons of cargo, as compared with 
S]/ 2 minutes for every 3 tons in the case of the DUKW'. 

(c) More efficient use would be made of driver 
manpower, for each amphibian driver would be re¬ 
sponsible for the transportation of more cargo. 

2. Stern Ramp. A stern ramp on the amphibian 
would ease many unloading problems. Artillery 
pieces and wheeled or tracked vehicles could be 
driven or towed out without delay. Palletized loads, 
fuel drums, and, in fact, almost any type of load could 
be dragged or rolled out without the necessity of lift¬ 
ing devices. With an adequate power hoist, the type 
of stern ramp and ramp seal in use on the LVT(3) and 
LVT(4) would be satisfactory for this purpose. 

3. Increased Water Speed. An amphibian designed 
from the ground up could unquestionably attain 
greater water speed than can the DUKW. Many of 
the appendages which cause such high resistance in 
the DUKW' could be built inside the hull of a com¬ 
pletely new vehicle. 

4. Improved Performance in Mud. An amphibian 
propelled on land by tracks in place of wheels could 
unquestionably operate on muddy terrain impassable 
for a DUKW or any other wheeled vehicle. 

o. Hull Dimension Limitations. W hile the advan¬ 
tages of an amphibian larger than the DUKW are ob¬ 
vious, the following factors must be borne in mind 
when considering the dimensions in the design of a 
new amphibian: 








CONCLUSIONS AND RECOMMENDATIONS 


109 


(a) Over-all size should conform to the dimensions 
of the ramp entrances of LSTs, LSMs, LSVs, and 
other rampecl landing ships which might serve as 
transportation for amphibians. 

(b) Angles of approach and departure should be 
suitable for operation across landing ship ramps, 
steep beaches, and coral reefs. DUKW angles of ap¬ 
proach (38 degrees) and departure (25 degrees) have 
proved favorable for such conditions. 

(c) Maneuverability on land, particularly in 
dumps, is essential. Over all width should probably 
be limited to 114 inches. 

(d) Driver’s vision should be good. 

A preliminary study has already been made of a 
proposed 15-ton, 3^-track amphibian. 1 ' Such an am¬ 
phibian would incorporate the features described 
above, and its Diesel power would provide the addi¬ 
tional desirable features of reduced fire hazards and 
reduced fuel consumption. 

It is recommended that this design be studied fur¬ 
ther and that a pilot model be constructed so that the 
possibilities of adopting it as a standard Army am¬ 
phibian can be more carefully explored. 

Such a new amphibian, however, should supple¬ 
ment rather than entirely supplant the DUKW, and 
any future amphibian production and training pro¬ 
grams should include both vehicles. In spite of its 
shortcomings, the DUKW will always have certain 
advantages over the larger amphibian. These in¬ 
clude: 

1. Superior ability to negotiate narrow trails, 
roads, and bridges. 

2. Greater land mobility and speed, making it de¬ 
sirable to use the DUKW for longer land hauls. 

3. Uonger land life than the 34-track amphibian, 
providing another reason for the use of the DUKW 
on long or rough land hauls. 

4. Suitability for stowage in davits on transports 
and similar vessels. 

5. Easier transportation and stowage on deck and 
in certain types of ship’s holds. 

If such 15-ton amphibians be adopted, it is recom¬ 
mended that they be operated by amphibian truck 
companies in the same way as DUKWs, except that a 
company should have only 25 15-ton amphibians in¬ 
stead of 50 DUKWs. Companies operating the larger 
amphibians should be placed together with DUKW 
companies under the operational control of amphib- 


h See Chapter 8 in this volume. 


ian truck battalion headquarters. Thus, in a typical 
operation, a battalion headquarters would have three 
companies operating DUKWs and two operating 
large amphibians. In this way, the battalion head¬ 
quarters could control both types of vehicle so that 
the large amphibians would handle all larger loads 
and make all the longer sea runs, while DUKWs 
would be used for the longer land runs. 

It is further recommended that such an amphibian 
be produced in two models, one for combat missions 
and the other for strictly supply functions. The com¬ 
bat model would be armored in its more vulnerable 
parts and would be fitted with interchangeable 
mounts for machine guns, rockets, flame throwers, 
and other weapons as developed. It could also serve 
as an amphibious firing platform for the 105-mm 
howitzer and other artillery pieces. 

462 Modifications 

As described in the beginning of this chapter and 
indicated in Tables 1 and 2, there was a serious time 
lag in making a change in production, even if the 
recommended change ever were approved, after field 
experience had indicated the necessity for it. In the 
meantime, the only way in which the change could 
go into effect was by having some exceptionally con¬ 
scientious ordnance unit in the forward areas or even 
the DUKW company itself able to find the time, 
labor, and materials to make the modification. 

The subject of production changes on such a 
vehicle as the DUKW requires a great deal of study 
in order that the many operational and mechanical 
difficulties experienced in the past may be avoided in 
the future. As with the spare parts supply problem, 
the failure to incorporate prompt changes in pro¬ 
duction was caused largely by the multiplicity of 
the channels through which recommendations for 
changes had to pass. 

It would seem that the best means for overcoming 
this difficulty in the future wotdd be to have accre¬ 
dited and highly competent personnel accompany the 
vehicle through all its major operations. Such per¬ 
sonnel should be empowered to communicate di¬ 
rectly with the ordnance authorities responsible for 
the production of the vehicle in the factories, and 
these ordnance authorities should be prepared to ac¬ 
cept and act without delay or reservation upon any 
recommendations sent in by the overseas observers. 
Furthermore, all vehicles which have already left the 









110 


THE DUKW: ITS APPLICATIONS 


assembly line should undergo the recommended 
change at the port of embarkation before they' are 
shipped overseas. 

463 Training 

Schools and Programs 

As already pointed out above, DUKW training in 
the United States was not adequate, and as far as pos¬ 
sible OSR1) gave amphibian truck companies addi¬ 
tional training at schools established overseas. This 
system, however, resulted in duplication of effort and 
a consequent delay in the time before units were 
ready for operation. Moreover, fuel, training aids, 
and school personnel were far less available overseas 
than on the mainland. In any future training pro¬ 
gram for amphibian operators, it would be desirable 
for more realistic and thorough training to be given 
in the United States so that units would be in first- 
class operating condition at the time of their ship¬ 
ment to the theaters. 

1. Such a school should be established at a location 
where training conditions are more satisfactory than 
those at Camp Gordon Johnston. There should be 
rough sea, heavy surf, strong currents, deep sand, 
mud, and coral so that drivers may have the chance to 
train under conditions at least as bad as those under 
which they will eventually be expected to operate. 
Fort Old, California, offers everything but coral. 

2. Whenever possible, units should be issued their 
own vehicles in the United States so that they can 
train on them rather than on school vehicles and so 
that they can modify and prepare their own vehicles 
for overseas operations. It will also be found that in¬ 
terest greatly increases when the students train on the 
same vehicles which they will use later in combat. 

3. Greater attention should be given to training 
officers so that they will know even more than the en¬ 
listed men drivers about the operation and mainte¬ 
nance of amphibians. During DUKW training in the 
United States, it was found that amphibian truck 
company officers were required to devote too much 
time to administrative affairs and not enough to 
DUKW operations, and many of them reported that 
they were not even permitted to drive DUKWs. A 
company cannot be expected to operate at maximum 
efficiency unless its officers thoroughly understand 
every aspect of the operation and maintenance of 
their vehicles. 

4. A closer liaison should be maintained with the 


theaters in which the vehicle is being used. In this 
way, students can be trained in the latest uses and 
techniques and can be warned against the mechani¬ 
cal and operational difficulties most recently encoun¬ 
tered in the field. 

5. A more flexible training schedule should be in¬ 
stituted. By maintaining a close liaison with the 
higher headquarters under which the units will even¬ 
tually operate, more information can be obtained on 
any special mission for which they will be used, and 
specialized training can be given accordingly. For 
operations demanding such special techniques as 
coral driving or river crossing, students should be 
sent to a location where suitable training conditions 
exist. 

Personnel 

In order that future amphibian truck companies 
can produce maximum results, qualification require¬ 
ments should be raised for driver personnel. It is not 
necessary that operators of amphibians should have 
a seagoing background; it has been found that the 
best results are obtained with men having truck driv¬ 
ing and stevedoring experience. Mechanical aptitude 
has been found very important. Men should be drawn 
from Army Classification Group 3 or better. Officers 
should be selected on the basis of their background 
and leadership qualifications. 

Publications 

Even after they had been written, there was a con¬ 
siderable delay in the distribution of DUKW train¬ 
ing manuals. This was due primarily to the time 
taken in putting the finishing touches on illustrations 
and other details after the text had been completed. 
As a result, in an attempt to produce a perfect publi¬ 
cation, the value of the manual was almost com¬ 
pletely lost; by the time the publication reached the 
men who needed it, the information it contained was 
largely out of date. 

I he development of new techniques, the changes 
in tactical doctrines, the necessity for field work to 
rectify the most recent mechanical weaknesses, and 
many other factors all necessitate alterations and ad¬ 
ditions to an amphibian operator’s manual at least 
every 6 months. Moreover, such information must be 
in the hands of the using units within 1 month of the 
date on which it is written or its value will be lost to a 
great extent. 






CONCLUSIONS AND RECOMMENDATIONS 


111 


4,6,4 Maintenance 

Maintenance Procedures 

While amphibian truck companies were equipped 
with second and third echelon tool sets, it often hap¬ 
pened that higher headquarters forbade the com¬ 
panies to do any work higher than light second eche¬ 
lon maintenance on their vehicles. It was believed 
that all third and heavy second echelon work on 
DUKWs should be performed by ordnance com¬ 
panies. This proved a mistake, for such ordnance 
companies were rarely equipped or trained to per¬ 
form such work as efficiently as could be done by the 
DUKW company mechanics with their specialized 
training and past experience. Moreover, this DUKW 
repair work was generally farmed out to ordnance 
companies without consideration of other work on 
hand, which already might have been more than ord¬ 
nance coidd handle expeditiously, ft should be 
pointed out that in such cases, if DUKWs or other 
amphibians are left standing without attention for 
only a week, serious deterioration results from salt 
water corrosion. 

In any future operations, it is recommended that 
amphibian truck companies be permitted to perform 
all repairs up to fourth echelon on their vehicles. 
Amphibians requiring such work will consequently 
be back in operation sooner, and the work will be 
more satisfactorily performed. 

Spare Parts 

In not one single operation during World War II 
was the DUKW parts supply system really satisfac¬ 
tory, and in many operations it was nonexistent. The 
reasons for this situation arc manifold, but in most 
cases it can be put down to the fact that there were 
just too many channels through which the spare parts 
had to pass between the factory and the DUKW com¬ 
pany motor pool. Therefore, it woidd seem that if a 
means could be devised for the elimination of some 
of the numerous channels, the vehicles would be in a 
better position to receive their parts when they are 
needed. 

In most cases, DUKW 7 companies were shipped 
overseas without any spare parts, but with the under¬ 
standing that they could pick up all they would need 
in the theater of operations. Naturally, for various 
reasons they were rarely able to get such parts even 
when the location and identity of the parts were 
known. It would be more satisfactory if companies, 


upon arrival at the port of embarkation, could re¬ 
ceive an automatic issue of at least a 90-day supply to 
lake along with their organizational equipment. It is 
also recommended that the spare parts issue lists as 
prescribed in SNL G-501 3 be revised to include a 
larger quantity of those items which have been found 
in operational experience to need most frequent re¬ 
placement. 

4,6,5 Operation 

Issue of Vehicles 

Except in very rare cases, DUKWs or other am¬ 
phibious cargo carriers should not be issued to units 
other than amphibian truck companies. If amphib¬ 
ians are required for some special mission besides 
cargo carrying, such as the transportation or firing of 
artillery or laying Signal Corps wire, a company or 
part of a company should be attached to the unit re¬ 
quiring their services for the duration of such a mis¬ 
sion and then immediately revert to their normal 
ship-unloading duties. The DUKWs will thus be 
operated by fully trained personnel who, moreover, 
will have better accessibility to spare parts supplies 
and maintenance facilities. In cases where this system 
was not adopted, results were unsatisfactory, not only 
because the DUKWs were poorly maintained and 
operated, but also because upon the termination of 
their primary mission they were either neglected in a 
parking area or used merely for land transportation. 

Functions of Battalion Headquarters 

The functions of an amphibian truck battalion 
headquarters were originally intended to be entirely 
administrative. In any operation in which more than 
two amphibian truck companies were involved, how¬ 
ever, the need for a headquarters to control and coor¬ 
dinate DUKW operation and maintenance was so 
imperative that the battalion headquarters were re¬ 
quested to perform these functions. In cases in which 
a battalion headquarters was not available, officers 
from the DUKW companies themselves were detailed 
to act as a control center, but this was not too satis¬ 
factory, since they did not have high enough rank and 
since, in addition, the companies were obliged to 
operate short of officers. 

In the future, if DUKWs or other amphibious 
cargo carriers are to be used on a large scale, they 
should be placed under the operational control of a 
battalion headquarters. Also, battalion headquarters 




112 


THE DUKW: ITS APPLICATIONS 


should be landed earlier and take control sooner than 
was the case in many past operations. At Okinawa, 
for example, although DUKW companies operated 
from D-Day on, the battalion headquarters did not 
come in and take over their control until a month 
later. In the meantime, since their control was com¬ 
pletely decentralized, the DUKW companies were 
not used to the best advantage: periodically one com¬ 
pany would be given much more work than it could 
accomplish, while other companies had DUKWs 
standing by because of no assigned work, and in most 
cases an excessive number of DUKWs was requested 
for individual missions. Individuals not familiar with 
DUKW operations have not often realized that there 
is an optimum number of DUKWs which can be effi¬ 
ciently used for a mission. They tend to believe that 
the greater the number of DUKWs assigned to a ship, 
the faster it will be unloaded. This is most emphati¬ 
cally not true. Not only are DUKWs wasted in such 
an arrangement, but dumps and roads are unneces¬ 
sarily congested. 

At Okinawa, if the battalion headquarters had 
been landed earlier, all the companies could have 
been released to them as soon as their original assault 
missions had been accomplished. Then, by coordi¬ 
nated control, the maximum use of all available 
DUKWs could have been insured. 

W EAKNESSES OF SHORE UNLOADING 

A study of DUKW operations during the war will 
disclose the fact that the inevitable limiting factor to 
tonnage rates were the conditions at the shore unload¬ 
ing points. Especially during the garrison phase, 
dumps could not or would not receive cargo at a rate 
equal to the maximum ship discharging rate. Not 
only did this condition affect DUKW efficiency but it 
also affected the entire logistic chain. 

Even the adoption of a transfer point system did 
not alleviate matters. This meant merely that while 
all available land trucks were held up in the dumps, 
a line of loaded DUKWs would be waiting at the 
transfer point for trucks into which their loads could 
be transferred, and meanwhile ships and hatch gangs 
lay idle. The addition of more DUKWs or more 
trucks to this cycle only increased land traffic conges¬ 
tion without expediting the flow of cargo into the 
dumps. 

Past shore unloading operations should be studied 
and the procedures improved so that dumps can be 
expected to receive cargo at maximum rates at all 


times. One of the first vital improvements would be a 
system in which dumps are constantly under the di¬ 
rect supervision of ranking officers who are thor¬ 
oughly aware of the problems of all the links in the 
logistical chain and who are familiar with such ex¬ 
pedients as the following: (1) The procurement from 
DUKW battalion headquarters of DUKWs dead- 
lined for water operation, in order to provide A- 
frames as additional unloading facilities; (2) the pro¬ 
curement of native or prisoner-of-war labor for dump 
work; (3) the use of a roller conveyor system for the 
sorting of mixed rations, thus making it unnecessary 
for a vehicle to go to more than one unloading point 
in a dump. 

Battalion Headquarters T/O 

For the battalion headquarters to perform its con¬ 
trol functions with maximum efficiency, an addi¬ 
tional officer with the rank of captain is essential. He 
should act as liaison with higher headquarters on the 
daily assignment of amphibians to their various mis¬ 
sions and should compile all operational data and 
reports. 

I'he T/O should also be increased by the addition 
of one sergeant and two Tec 5, clerks, general, to the 
operations section. The inclusion of a medical de¬ 
tachment in the battalion headquarters would also be 
of great value and should consist of a battalion sur¬ 
geon and a minimum of 10 enlisted men. Much time 
and transportation were used in past operations in 
taking patients from the companies to hospitals. 
Once at the hospital and regardless of the degree of 
seriousness of their cases, these patients were gen¬ 
erally evacuated. It is safe to say that, instead of being 
evacuated and leaving the companies permanently 
short-handed, at least 50 per cent of the personnel 
evacuated out of amphibian truck companies in Pa¬ 
cific operations could have been returned to their 
units after treatment by a battalion medical detach¬ 
ment. 

Amphibian Truck Company T/O 

For round-the-clock operations over an extended 
period, the strength of an amphibian truck company 
as organized in World War II is not sufficient. DUKW 
companies were sometimes so hard-pressed that they 
were forced to break down their system of having 
drivers permanently assigned to their own vehicles. 
I his invariably resulted in a deterioration in driver 


maintenance and consequent higher vehicle deadline 





CONCLUSIONS AND RECOMMENDATIONS 


11! 


rates, which in turn naturally cut down tonnage fig¬ 
ures. A strength of 210 enlisted men is recommended 
for an amphibian truck company with 50 DUKWs. 
Instead of 11 as now prescribed, at least 15 of these 
men should be mechanics. In the case of a company 
operating 25 15-ton amphibians, the number of 
drivers would not be as great, but it is believed that at 
least 20 mechanics would be required for the larger 
vehicles. 

Battalion Headquarters T/E 

It is recommended that the following equipment 
be added to the T/E of the amphibian truck bat¬ 
talion headquarters: one Bl)72 switchboard, one 
squad tent, four pyramidal tents, two i^-ton trucks, 
and one SCR-608 radio. The last item is essential for 
efficient control of the operation. With this radio, 
contact can be maintained with all the company com¬ 
mand posts, beach control points, and ship control 
points. 

Amphibian Truck Company T/E 

It is recommended that the following additions be 
made to the T/E of an amphibian truck company: 
one 10-ton wrecker, one 750-gallon, 2i/c>-ton, 6x6 
tanker (with pump), one mounted machine shop, one 
parts trailer, four-wheel, and one 250-gallon water 
trailer. 

In every instance where companies were able to 
procure these items, they proved of great value and 
assisted in increasing tonnage rates. If the tanker and 
the water trailer are not available, then amphibians 
that might be hauling cargo must be used for the 


daily transportation of fuel and water to the company 
area. A wrecker is necessary for salvage and recovery 
work. On many occasions, DUKWs were lost as a re¬ 
sult of swamping and broaching in the surf while 
hung up on bad reefs or wreckage. Had a wrecker 
been available, such DUKWs could have been pulled 
ashore before incurring serious damage. A wrecker is 
also needed to recover vehicles that have become bel¬ 
lied in soft mud or overturned in ditches, or to tow to 
the motor pool vehicles that have been damaged by 
land mines or shellfire. The wrecker can also expedite 
the repair of vehicles in the motor pool by lifting the 
front or rear ends or removing the motor or other 
assemblies. 

It is also recommended that the two cranes now in¬ 
cluded should be eliminated from the T/E of an am¬ 
phibian truck company. While those cranes were of 
benefit to the over-all operation, they were a liability 
to the company itself. When the company is required 
to operate them, four men are lost as DUKW opera¬ 
tors. In most cases, both cranes and men were taken 
permanently from the company by higher headquar¬ 
ters and assigned to duties which did not in any way 
concern DUKW operations. 

The provision of shore unloading facilities should 
not be the responsibility of amphibian truck units, 
except in such cases as the unloading of artillery and 
ammunition by DUKW A-frame during the assault 
phase before the landing of other kinds of cargo¬ 
handling equipment operated by other Service 
branches. Such shore unloading facilities as cranes for 
use in dumps and at transfer points should be in¬ 
cluded in the T/E of dump service companies or 
similar organizations. 







The Weasel (“ ... any of certain small slender-bodied carnivorous mammals of the genus Mustela . . . very active, bold 
turn white in winter on routine winter snow patrol. Cold winter air condenses exhaust gases into a white 

vapor. 



114 









Chapter 5 

THE WEASEL 


Summary 

he weasel," a light track-laying cargo carrier, was 
developed in the spring and summer of 1942 for a 
military operation against the Germans in Norway 
proposed for early in the winter of 1943. Before the 
invasion plans were cancelled, it went into limited 
production as a vehicle which could negotiate hard 
ground and snow, climb relatively steep snow-covered 
mountains, and be transported by air and dropped 
from aircraft. 

This first model, the T-15 Weasel, finally standard¬ 
ized as the Cargo Carrier M-28, was the forerunner of 
the T-24 Weasel, which was designed in 1943 and 
later standardized as the Cargo Carrier M-29. With 
redesigned hull, power train, bogie wheels, track, sus¬ 
pension, and rearrangement of passenger and cargo 
layout, it went into production for use in snow, mud, 
swamps, and marshes, where other vehicles could not 
operate, and served in both the European and Pacific 
theaters. 

Another conversion resulted in the development 
of the Ark or M-29C Weasel, an amphibious vehicle 
able to operate not only over snow, mud, and hard 
ground but also in deep water. It is ecpiipped with 
special bow and stern cells to provide added buoy¬ 
ancy, and with rudders, skirts, and other shrouding 
devices to permit water propulsion by means of its 
own tracks. 

Approximately 16,000 units were produced by the 
summer of 1945 and about 8,000 more were on order. 
The Weasel was used by the U. S. Army, Navy, and 
Marine Corps and by Allied military groups as a gen¬ 
eral purpose vehicle and specifically for evacuation 
of casualties, wire-laying, reconnaissance across mine 
fields, supply work in snow and mud, special rescue 
missions, and transportation of personnel and equip¬ 
ment. 

As part of this development, all available snow 
vehicles were studied, summer test grounds were es¬ 
tablished in the Columbia Ice Fields in Canada, and 
a concurrent study was conducted on the physical 
properties of snow and their relation to the perform¬ 
ance of snow vehicles to make possible a prediction, 


a Project OD-65. 


by means of weather forecasts, of the performance of a 
task force mounted on Weasels, in comparison with 
the performance of defending ski troops. 

51 THE PROBLEM 

On May 1, 1942, the Director of the Office of Scien¬ 
tific Research and Development [OSRD] was asked 
by the Chief of Staff, U. S. Army, to develop a snow 
vehicle to be used in an airborne invasion of Norway 
in the winter of 1942-43. 

In the words of the Prime Minister’s Mission sent 
from Great Britain to expedite this operation, the 
vehicle should literally convert snow from a barrier 
into a highway. It should be able to traverse snow, 
dry land, mud, rocks, and water, and to be carried in 
gliders or dropped from heavy bombers. Delivery of 
the first of 600 production models should begin in 180 
days for the training of the invasion troops. 

This project was assigned to Division 12 of the 
National Defense Research Committee [NDRC], 
working directly with the Assistant Chief of Staff, 
G-4, War Department General Staff. The general re¬ 
quirements were that the new vehicle be able to fit in 
the bomb bay of the British Lancaster bomber or into 
the American glider, that it be capable of parachute 
descent on to bare lake ice, and that it be ready to 
move off under its own power immediately after land¬ 
ing. (Later specifications called for slinging the 
vehicle underneath the American C-54 cargo plane.) 
In snow it should have good speed on the level, high 
maneuverability in forests, and be able to climb well 
and to traverse sidehills. It should be able to cross 
bare rock and railroad tracks, and to get through 
spring freshets. It should carry a 1,200-pound pay- 
load. Since the distance to be traveled by each vehicle 
in the invasion would be an average of less than 100 
miles, of which 90 would be on snow and 10 on hard 
ground, ice, or rock, the life of each unit was set at 
only 1,000 miles. 

From these general requirements there later 
emerged the following functional specifications: 

1. Maximum beam.60 in. 

2. Maximum length.156 in. 

3. Maximum profile.50 in. 





115 






116 


THE WEASEL 



Figure 1. Propeller-driven Aero-Sled stalled on slight 
slope. 



Figure 2. U. S. Forest Service Snow-Motor, with single 60- 
inch track and driver’s cab supported by rear skis. 



I 


Figure 3. Eliason toboggan, driven by single 10-inch 
track, forced downwards by spring reacting against dead 
weight of vehicle. 

*8R 




Figure 4. Tucker Sno-Cat (M-7 Snow Tractor) used by 
Army Air Forces for rescue and ground reconnaissance 
missions but later discarded. 




Figure 5. The Bombardier, driven by tracks and steered 
by forward skis. 


Figure 6. Standard 14-ton, 4x4 jeep equipped with 
17:00x20 airplane tires. 



Figure 7. The Louisiana Swamp Buggy, designed for 
operation in swamps and sheltered water. 



Figure 8. The Utah snowmobile, one variety of conven¬ 
tional Caterpillar tractor modified for use in snow, with 
forward skis for steering. 














T-15 WEASEL 


117 


4. Military payload (including 

2-man crew). 1,200 lb 

5. Center of gravity.Low as possible 

6. Speed on level, in light pow¬ 

der snow.25 mph 

7. Speed in water.Nominal 

8. Angle of climb on turf ... 45 degrees 

9. Angle of climb on light pow¬ 

der snow.25 degrees 

10. Maximum turning radius . . 144 in. 

11. Minimum power-weight ratio 40 hp per ton 

12. Cruising radius in rugged 

country. 225 miles 

13. Life expectancy. 1,000 miles 

14. Noise in operating.Minimum 


All these requirements were based on operations at 
an altitude of 3,000 feet, in a temperature range from 
—40 to +50 F. 

It was apparent at once that no existing snow ve¬ 
hicle could meet these requirements, and further¬ 
more that insufficient information was available on 
the physical properties of snow to permit the applica¬ 
tion of orthodox design procedures. Little seemed to 
be known about the shear strength of snow and still 
less about the change of shear strength as a function 
of the controlling factors—or, indeed, even the iden¬ 
tity of these factors. 14 

5.2 THE T-15 WEASEL 

As presented to Division 12 of NDRC, the problem 
had its fantastic elements. It was necessary to invent 
a snow vehicle without sufficient engineering knowl¬ 
edge of snow, to decide on the preliminary design 
before tests on it could be made, to submit this pilot 
model to field trials in snow in the middle of summer, 
and to deliver the production model in 180 days, of 
which an estimated 40 woidd be consumed in get¬ 
ting out the pilot models and 130 in tooling for 
production. 

5 21 Design Procedure 

With every emphasis laid on speed and with the 
full cooperation of British and American agencies 
which had previously investigated transportation 
over snow, work began at once on a study of existing 
vehicles and on a consideration of contractors able 
to design and build the new device. 


The Prior Art 

Various types of snow vehicles were already in ex¬ 
istence, most of them designed for sport or for rural 
mail delivery. These, together with experimental 
equipments previously studied by the U. S. Army 
Ordnance Department and the Winter and Moun¬ 
tain Warfare Board and by the Prime Minister’s 
Mission, were reviewed at once and the most promis¬ 
ing types were selected lor test. 

A telephone survey of North America showed that 
the best and most accessible location of spring snow 
was at Soda Springs, California, and test units began 
arriving there on May 4. These and later tests con¬ 
firmed the tentative conclusions derived from a study 
of the designs of the equipments concerned. 

Vehicles driven by an air propeller, such as the 
Aero-Sled (Figure 1), were found to develop high 
speed on the level, but they have low starting torque 
even on the level and are unable to climb grades of 
much more than 3 degrees. Their dimensions inher¬ 
ently prevent use in the prescribed method of air 
transport. They were the noisiest vehicles tested. Fi¬ 
nally, a vehicle of this design with sufficient power to 
meet the performance requirements on snow and 
with corresponding propeller diameter would be un¬ 
able to go through wooded country and, in any event, 
could not travel over bare dry ground. 

Two types of single-track vehicles were considered, 
one with a 60-inch track and one with a 10-inch track. 
The broad-track design (Figure 2) was eliminated 
since it could not meet the requirements for speed, 
climbing, or maneuverability, and the narrow-track 
design (Figure 3) because it tends to dig into deep 
snow and into snow-covered grades. 

Two types of double-track, ski-steerecl vehicles ap¬ 
peared to have useful characteristics. The Tucker 
Sno-Cat or M-7 Snow Tractor (Figure 4), which car¬ 
ries 75 per cent of the weight on a pair of tracks aft 
and 25 per cent on a pair of forward-running, steer¬ 
able skis, climbs quite steep grades, performs well in 
deep snow, and is particularly easy to turn on the 
level, but as designed does not give enough speech 
(A limited number of these vehicles were procured to 
meet Army Air Forces requirements, but as the result 
of field experience the design was abandoned.) The 
Bombardier (Figure 5), essentially an automobile 
converted into a half-track and equipped with skis 
instead of front wheels, gives high speed on the level 
but performs poorly on gentle slopes, and has high 
fuel consumption. 









118 


THE WEASEL 



Figure 9. Large twin Archimedean screw vehicle on 
medium moraine. 


All vehicles with forward skis were found to be 
handicapped by an inability to make turns at high 
speed, particularly when running downhill over un¬ 
dulating snow. On bare ground, skis have high resist¬ 
ance, and the vehicle is difficult to steer. 

It was apparent from their performance that a 
snow vehicle should be supported entirely on its 
driving members, and that the location of the center 
of gravity is a critical factor in its performance. 

A vehicle with very large balloon tires, such as a 



jeep with 17.00x20 airplane tires (Figure 6), gives 
high speed on the level but unsatisfactory perform¬ 
ance on even mild slopes. It is halted by gentle hills 
in light powder snow, and lacks traction for adequate 
control in steering. Consideration was also given to 
vehicles with gigantic balloon tires, such as the Loui¬ 
siana Swamp Buggy (Figure 7), but these could not 
meet the dimensional limitations, presumably would 
have insufficient traction on sloping ice, and exceeded 
the weight limitation. 

Conventional Caterpillar tractors (Figure 8) have 
low speeds even on the level and are unable to climb 
snow grades much greater than 8 to 10 degrees. They 
tend to dig in at the rear when climbing. 

Tests with vehicles driven by twin Archimedean 
screws (Figures 9 and 10) showed that this type of de¬ 
sign does not lend itself to high speed on level snow, 
partly because of the high frictional losses inherent in 
the high ratio of peripheral speed to speed of ad¬ 
vance; that they cannot travel at high speed over bare 
rock or on roads; and that the basic design seemed to 
necessitate exceeding the allowable beam or profile 
dimensions. If the engine and cab are located be¬ 
tween the screws, the maximum permissible beam is 
exceeded, and if they are placed above the screws, the 
maximum profile is exceeded and lateral stability is 
greatly reduced (Figure 12). Tests of a vehicle driven 
by a single Archimedean screiv and stabilized by out¬ 
riggers (Figure 11) indicate no inherent advantages 
over the double-screw design. 

A study of these and related designs and of the 
performances in California, which were later con¬ 
firmed in other field trials, resulted in the conclusion 
that no available snow vehicle could meet the mili¬ 
tary requirements. 14 

Basis of the Design 

Seven days after work began, the primary specifica¬ 
tions for the vehicle were confirmed. From the tests 


t 



Ficure 10. Small twin Archimedean screw vehicle dig¬ 
ging into soft snow on slight grade. 


Figure 11. Tucker spiral-drive snow sled, a single Archi¬ 
medean screw vehicle stabilized by outriggers. 


1 








T-15 WEASEL 


119 




f i i 

wM. 


FRONT VIEW 



BOTTOM VIEW 






- f 

o 

( 


V 



CD 




j 

--I79"0 A-► 



BOTTOM VIEW 



FRONT VIEW 


SIDE VIEW 


5 


FRONT VIEW 


Arrangement 1. Two cylinders each 22 inches in diam¬ 
eter, 205 inches long, 31/^-inch thread, 18-inch lead, bear¬ 
ing pressure 1 psi. 


Arrangement 2. Two cylinders each 22 inches in diam¬ 
eter, 136 inches long, 3i/£-inch thread, 18-inch lead, bear¬ 
ing pressure 1 psi. 

Arrangement 3. Four cylinders each 22 inches in diam¬ 
eter, 110 inches long, bearing pressure 1 psi. 


I ft C A B| 


I- . i ■ - ■ =3. 

V 

,_1 c ~\ 

“ 4 L° aT ! ! 

1 

CD 

<D 

Li 



t ■ a r 

A/ V 




SIDE VIEW 



Arrangement 4. Four small cylinders. 

Arrangement 5. Two cylinders, each 22 inches in diam¬ 
eter, 123 inches long, 3i/£-inch thread, 18-inch lead, bear¬ 
ing pressure 1 psi. 

All arrangements. Payload of 1,200 pounds including 
two men; total weight loaded 4,300 pounds. 



Figure 12. Preliminary plans for Archimedean screw vehicles. 


ftONFIDENTIAI^ 

































































































































































































































































120 


THE WEASEL 


iii California and elsewhere, it was apparent that air 
propellers and large tires are impractical, that for¬ 
ward skis are ineffective in steering on sidehill tra¬ 
verses and on downhill runs, and that the entire 
flotation of the vehicle should be supplied by the 
tractive means—in short, that a track-laying vehicle 
would be the most satisfactory solution. 

Ignorance of the physical properties of snow made 
it impossible to arrive at an over-all design by rational 
steps. It was clear, however, that although the vehicle 
should preferably have a unit ground pressure no 
greater than that of an average skier (about 0.5 psi 
for a 200-pound man on a pair of conventional slalom 
skis), such a value would be difficult and probably 
impossible to achieve. Preliminary weight considera¬ 
tions revealed that even a value of 1.0 psi could not 
be readily attained (such vehicles as the M-4 General 
Sherman tank and the German MK-VIB King Tiger 
tank have unit ground pressures from about 14.3 to 
14.7 psi), and it was decided to assign no limit to this 
value but to keep it as small as possible. 

Since it was thought that the L/T ratio (L = length 
of track on ground and T = tread) of a track-laying 
vehicle on snow should not exceed 2.00 if steering 
were to be feasible, and since the beam was already 
limited to 60 inches, it followed that the ground con¬ 
tact length should not exceed 90 inches, depending 
on the tread. The over-all length should not exceed 
about 190 inches, depending on the design of the 
ends. 

The center of gravity for climbing should be for¬ 
ward of the longitudinal mid-point of the ground 
contact area. For descending, it should be not too far 
forward of that mid-point. For sidehill traversing, it 
should be as low as possible. 

For travel over snow, it seemed that the tracks 
should be designed to prevent packing of wet snow in 
them, that the action of the track plates in going over 
the sprockets should tend to remove snow from be¬ 
tween the grousers, and that the depth of the grousers 
should be considerable. (It was found later, however, 1 
that although deep grousers assist somewhat in climb¬ 
ing, they exact a very heavy penalty on hard-packed 
snow, ice, and hard roads because of the concentrated 
shock loads.) 

Accordingly, the War Department General Staff 
was advised that the design most likely to meet the 
military requirements appeared to be a conventional 
track-laying vehicle with controlled differential steef^ 
ing, a beam of 60 inches, and a unit ground press/ire 


to be a minimum consistent with good steering. 14 A 
broad directive was consequently issued to “design, 
build, develop and test one or more pilot models of a 
track-laying, airborne, amphibious, snow vehicle to 
carry a payload of 1,200 pounds up a 25-degree slope 
in deep snow and to have a maximum speed on the 
level in packed snow of 35 mph.” 

This vehicle was christened by Division 12 as the 
Weasel (“. . . any of certain stnall slender-bodied 
carnivorous mammals of the genus Mustela . . . very 
active , bold . . . turn white in winter . . On May 
17, work began on the pilot model designs. b 

Design Development 

The first of the pilot models was developed to meet 
the original military requirements for use in either 
snow or water operations, and was to afford an oppor¬ 
tunity to determine whether the maximum L/T ratio 
as informally established by the Army would be satis¬ 
factory. Inasmuch as the hull, engine, and drive mech¬ 
anism presented few new questions for the contrac¬ 
tor’s engineers, the design problem became essentially 
a development of track and suspension components. 

The track is front-driven by a controlled steering 
differential. The power plant is located approxi¬ 
mately amidships. Eight bogie wheels, arranged in 
four pairs on each side, carry the vehicle load on each 
flexible-cable, band-type track. Each pair of bogies is 
connected by longitudinal semi-elliptic springs pivot¬ 
ally anchored to suitable outriggers attached to the 
hull. The suspension provides 89 inches of track on 
the ground and a 45-inch tread, giving a length of 
track on the ground to tread ratio of 1.97. Each track 
is 15 inches wide and, on the basis of area of track in 
contact with the ground, the unit ground pressure is 
2.62 psi at zero penetration. The vehicle, weighing 
approximately 7,000 pounds with full cargo load, has 
provisions for a crew of two and storage space in 
the hull sponsons for their necessary equipment and 
supplies. 4 

This amphibious pilot model (Figure 13) was com¬ 
pleted in 38 days. After conferences with the various 
authorities, it was decided to set its L/T ratio at the 
high value of 1.97, with an over-all length of 196 
inches. This was done partly to explore the upper 
limit of the L/T ratio and partly to permit incor¬ 
poration of a propeller for water drive. A few days 
after this model was started, and because of fears that 

b This investigation was conducted by the Studebaker Cor¬ 
poration, South Bend, Ind., under OSRD contract OEMsr-635. 






T-15 WEASEL 


121 




Figure 13. Plan and elevation diagram of early experimental amphibious snow vehicle. 


its performance would be unsatisfactory as a result of 
its high L/T ratio and its weight, a second and non- 
amphibious design was begun with an L/T ratio of 
1.6 and about half the weight. 

The amphibious pilot model has a width of 60 
inches, a height of 50i/o inches, a tunnel stern, and a 
propeller driven from a power take-off mechanism 
for water propulsion, as noted above. 

In the first ground tests, the amphibious pilot 
model was tried in marshy ground and a weedy lake. 
No difficulty was encountered in negotiating soft 
ground and weedy water, but as soon as the vehicle 
was in deep water fairly clear of weeds, steering with¬ 
out grousers on the track was found to be practically 
impossible. The unit was then taken to the St. Joseph 
River where, with the tracks stationary and propellers 
used for propulsion, a forward speed of about 1 to 2 
mph was attained, but the vehicle did not respond to 

\ 


the rudder control. No difficulty was encountered in 
getting it in or out of the water up a reasonable bank 
from shoal water. In general it appeared to give the 
required performance over the terrain over which it 
was tested, but it was found impossible to steer either 
on land or in water. 15 

In the nonamphibious pilot model, the over-all 
length was reduced, the track width increased, and 
the L/T ratio reduced to 1.6. Four models were hand¬ 
made from this second design in 35 to 55 days each, 
and were eventually put to test in sand and later in 
snow. These units were used for a quick investigation 
of the critical components of the vehicle. 

In the selection of the most useful track, two types 
were studied: a woven wire mesh type, c which was 


c Manufactured by the Firestone Tire and Rubber Co., 
Akron, Ohio. 
















































































THE WEASEL 





Figure 1 -1. Goodrich semiflexible track bands. 


discarded because of excessive friction, and a semi¬ 
flexible type d (Figure 14) made of two molded rub¬ 
ber bands, each reinforced longitudinally by four 
continuous steel cables, to which are attached a num¬ 
ber of steel cross members at 3-inch intervals. The 
grouser plates and guides are attached to the cross 
plates. 


<1 Manufactured by the B. F. Goodrich Co., Akron, Ohio. 


Several different types and sizes of bogie wheels and 
springs were tested. Track throwing difficulties en¬ 
countered with straight bogie wheels led first to the 
use of angular bogie wheels and finally to angular 
swivel bogies (Figure 15). The latter is substantially 
an axle on each end of the spring of the angular 
bogie, about which the wheel assembly can articulate 
on a longitudinal tfxis for a distance of a 26-degree 
included angle. This permits the track to twist farther 
before the guides and guide wheels are forced to part, 
thereby permitting the track to stay on as the angu¬ 
larity increases or until the stops are met. 

The bottom leaves of the bogie springs are wrapped 
around the spring eyes, and clips are added to prevent 
separating. Steps were added to limit the backward 
tilt of the front bogie assembly to 12 degrees down¬ 
ward and 16 degrees upward. This prevents buckling 
under when certain types of terrain are encountered. 

The track idler wheel assembly was originally made 
up of a pair of disks so formed that the guides of the 
track are retained by them in the form of a narrow 
throat. This was later changed to a wide throat so 
that the track can readily feed back into place if it 
starts to come off. Additional flanges were used to 
carry a fabric belt tire to support the rubber belt of 
the track. The small lightening holes were eliminated 
by use of a sharp-edged center disk with large cut¬ 
aways and spoke reinforcements, while the rubber 
tire section was changed to a wide rubber band, which 
proved to be an efficient de-icer. 

As with the idler, it became necessary to modify the 
sprocket wheel by making larger openings for ice 
clearance and replacing the rubber fabric tire with a 
flat band of rubber. 

Since there was no basis to support a rational de¬ 
sign procedure, work on the grousers and grouser 
plates constituted one of the most extensive parts of 
the experimental program. The grouser plate started 
originally as a ribbed steel plate turned up a little at 
each end and provided with suitable mounting holes. 
Many types and design variations were made but, 
with the exception of the addition of a large center 
clearance hole to prevent ice from packing and a % 6 - 
inch coating of rubber on the ground contact side, 
the ribbed plate type finally used (Figure 16) is little 
different from the original design. 

After a trial of many shapes, the best grouser was 
found to be a unit 1 inch high, 14% 2 inches long, and 
straight across the front or driving side of the grouser 
plate. A short straight grouser 6 inches long is cen- 


'Txt 


Jfirrnsw 










T-15 WEASEL 


123 



Figure 15. Diagram of angular and swivel bogies devel¬ 
oped for T-15 Weasel. 


trally located at the rear side. These grouser plate 
assemblies are coated on the bottom with a % 6 -inch 
layer of rubber and are permanent with every shoe. 
Provision is also made for a clamp-on involute type 
grouser, 2 11 / 1G inches high, to be attached to every 
other plate when conditions warrant. 

The track guide wheels were designed to guide the 
track at the top as well as to prevent excessive slap¬ 
ping when vibrations set the track in motion. Later a 
3^-inch endwise movement was provided to reduce 
wear on the guide wheels. 

In early tests, the vehicle displayed a tendency at 
high speeds to swirl powdered snow, which in turn 
was sucked into the air inlet and formed ice on the 
motor. In addition, certain types of snow would be 
thrown over the rear air chute to the radiator, where 
it melted and ran into the hull. Metal snow shields 
were consequently provided to protect the engine, 
and boxes were installed on each side to protect the 
radiator. 

Various types of steering differential were con¬ 
sidered, and steering ratios from 1.61:1 to 2.14:1 


were tried. The most satisfactory was one with a 
1.61:1 steering ratio, a transmission ratio of 1.15 high 
and 2.29 low, an axle ratio of 5.86, and an over-all 
axle of 6.75 high and 13.5 low. 15 

5 - 2 - 2 Test Procedure 

While these pilot models were under construction, 
representatives of Division 12 instituted a search for 
proving grounds where the models could be tested 
under appropriate security on various types of snow. 
With the cooperation of the State Department, ob¬ 
servers were flown under diplomatic passport to the 
Argentine and Chilean Andes, but reported that no 
suitable areas were available, partly for security rea¬ 
sons and partly because of an open winter. 

Another expedition was flown to Alaska for the 
double purpose of finding a proving ground and mak¬ 
ing preliminary tests of the shear strength of snow as 
developed by various alternative grouser designs. In 
the search by air for proving grounds, the observers 
looked for any powder snow being blown by ground 
winds, or the plane was banked at an altitude of 100 
feet so that the propeller wash could raise any powder 
snow present. Exploration of all accessible areas, 
however, demonstrated that there were no suitable 
grounds available in Alaska, neither in known glacial 
areas, where no powder snow was found below an 
altitude of 8,000 feet, nor in the arid and glacierless 
Endicott range in northern Alaska, where glaciers 
had been located by local “experts.” 

Finally an expedition to the Columbia Ice Fields 
found that the 400-square mile residual continental 



Figure 16. Inner side of grouser plate (top left), grouser 
and grouser plate (top right), and assembled unit devel¬ 
oped for T-15 Weasel. 



















































124 


THE WEASEL 



Figure 17. Loading juilot model of T-15 Weasel into C-47 cargo plane for transportation from South Bend, Indiana, 
to Columbia Ice Fields. 


ice sheet 60 miles north of Lake Louise and 9,000 feet 
above sea level offered the best proving ground avail¬ 
able and accessible in either North or South America. 
Although the snow was not powder but corn, and 
obviously due to get wetter, the site was selected for 
the field trials. 

Necessary roads were built on to the snout of the 
glacier by the Canadian National Park Service, the 
U. S. Army, and Studebaker, a 5-mile test track pre¬ 
pared, temporary housing constructed and photo¬ 
graphic laboratories, garages, and engineering quar¬ 
ters set up. The camps were operated by the 87th 
Mountain Infantry Regiment. The pilot models were 
brought there, one of them by plane (Figures 17 and 
18), together with other snow vehicles to be used in 
comparative studies. 

During the month of August, numerous test runs 
were made to determine the operation of the Weasel, 
its rolling resistance, its maximum speed, its hill¬ 
climbing ability, and its maneuverability. After a 
warm spell, when testing became impossible, the field 
trials were resumed at the end of September. 

When parts failed during the trials, suggested rede¬ 
signs were telephoned to the factory where improved 
parts were made up immediately, and the new parts 
were shipped to the ice fields for testing. By use of air 
transport service, replacements could generally be 
obtained in as little as 36 hours, making it possible 


to maintain the research in spite of numerous fail¬ 
ures in the early designs of bogie, track, and suspen¬ 
sion parts. A jeep and airplane shuttle service be¬ 
tween the ice fields and Toronto made it possible to 
have 16- and 35-mm films of all tests demonstrated at 
the camp for analysis within 48 hours, and to present 
to Army observers a complete record of the perform¬ 
ance of all vehicles under all test conditions. 

While these tests were under way, another group 


I'Igure 18. Pilot model of T-15 Weasel secured in cargo 
plane. 




























T-15 WEASEL 


125 



Figure 19. Side view of final pilot model of T-15 Weasel. 


of investigators conducted a basic study of the physi¬ 
cal factors of snow in an attempt to obtain funda¬ 
mental knowledge to be used in tactical operations 
with the Weasel and in any future modifications.® 

In order to determine the possibility of landing the 
Weasel by parachute, special tests were conducted at 
South Bend, Indiana, and Wright Field, Dayton, 
Ohio, under the supervision of the War Department 
General Staff. 

5 - 2 - 3 Results 

Design of the T-15 Weasel 15 

The final pilot model of the nonamphibious T-15 
Weasel is shown in Figures 19 to 22, with a longitudi¬ 
nal section shown in Figure 23. In this model the 
over-all length is 132 inches, the width is 60 inches, 
and the height is 67 inches with the top and 49 inches 
without it. The length of track in contact with the 
ground is reduced to 62 inches, giving a ratio of 
length of track on ground to tread of 62/42 or 1.48. 
The track width is increased to 18 inches, giving a 
unit ground pressure of about 2.05 psi at 1-inch pene¬ 
tration and with a gross weight (including 1,200- 
pound payload) of 4,600 pounds. Although the 

e These studies are reported in Chapter 18 of this volume. 


model is shorter than the amphibious unit described 
above, the cargo volume is about the same. 

The center of gravity is about 24 inches above the 
ground and 46 inches ahead of the center line of the 
idler. 

The suspension consists of four bogies on each side, 
arranged in pairs and connected together by com¬ 
pound semi-elliptic springs which are pivotally 
mounted to outriggered cross members forming 
part of the main hull framework (Figure 24). The 
final bogie design includes cambered bogie wheels 
mounted in pairs and pivoted on their connection 



Figure 20. Rear view of final pilot model of T-15 Weasel 
with top removed. 

















126 


THE WEASEL 



Figure 21. Front view of the final pilot model of T-15 
Weasel. 


with the suspension springs. The cambered bogie 
wheel and guide flange construction provides a line 
contact with the track guide lugs, and also produces 
a diverging guide throat which gives more clearance 



Figure 22. Top v iew of final pilot model of T-15 Weasel, 
showing accommodations for driver and one passenger. 


for variations in the angle of approach of the track 
guide to the bogie over rough surfaces. 

The Weasel is powered with an L-head. liquid- 
cooled, six-cylinder Studebaker Champion engine lo- 


VEHICLE DECK 



DECK COAMING 


BULKHEAD 


GUIDE 

WHEEL 


ENGINE 


TRANSMISSION 


drive 

WHEEL 


AXLE UNIT 


Figure 23. Elevation diagram of final pilot model of T-15 Weasel. 



















































































































T-15 WEASEL 




Figure 25. Transmission and flywheel end of engine 
located aft of driver’s compartment, T-15 Weasel. 


Performance 16 

To test maximum climb in the Columbia Ice 
Fields, the pilot models were driven up Mount Castle- 
guard (Figure 27) on a gradually increasing slope. 
The angle of grade was measured when the track 
began to slip so that further forward movement 
ceased. The maximum grade could usually be 
climbed only at a very low speed, generally 2 mph, 
because if the track once started to slip, traction 
could be regained only by a fresh start. During these 
tests it was noted especially that the Weasel would 
not stay in a straight line but would veer off to the 
right or left depending somewhat upon the general 
slope as well as upon the ruggedness of the under¬ 
neath snow crust. 

With I 1/2 to 2 inches of powder snow over crust, 
the Weasel was able to climb grades up to 21.8 de¬ 
grees, with an average maximum under these condi¬ 
tions of 19.8 degrees. In 7 to 8 inches of light snow, 
the average maximum was 24.15 degrees. 


steel. The rear and side walls of the rear air duct and 
the front wall of the cargo boxes are made of armor 
plate to protect the engine cooling system and the 
rear of the hull. 


Figure 24. Production model of angular swivel bogies 
used in T-15 Weasel. 


catecl at the rear of the hull (Figure 25). The flywheel 
end of the engine is connected to the driving axle at 
the front by means of a single plate clutch, a conven¬ 
tional transmission, a propeller shaft, and two needle- 
bearing type universal joints (Figure 26). The plane¬ 
tary type two-speed axle provides differential steering 
and, together with the transmission, six forward gear 
ratios and two in reverse. 

The hull is welded 18-gage, 0.050-inch thick sheet 


Figure 26. Forward end of driver’s compartment, show¬ 
ing instrument panel, steering levers, and connections to 
drive wheels, T-15 Weasel. 












128 


THE WEASEL 



Figure 27. Pilot model of T-15 Weasel climbing 20-clegree slope on Mount Castleguard, Columbia Ice Fields. 


On dry turf (Figure 28) it successfully climbed 45- 
degree grades. 

In maximum speed tests, the average top speed at 
an altitude of 8,450 feet was found to be 20.78 mph 



Figure 28. Pilot model of T-15 Weasel negotiating 25- 
degree grade on dry turf. 


in 1 1/2 to 2 inches of powder snow over crust (Figure 
29). During these runs, it was noted that, if the snow 
or ice were rough, the vehicle would pitch at high 
speeds. While this was not too objectionable under 
most conditions, it did create a hazard when rough 
snow and ice or rough moraine was encountered. On 


* 

Figure 29. Pilot model of T-15 Weasel can achieve 20.78 
mph on level powder snow over crust. 












T-15 WEASEL 


129 



Figure 30. “Inherent increase of climb” of about 4 de¬ 
grees is evident in downhill runs by pilot model of T-15 
Weasel. 

a hard, level surface, the Weasel could attain a speed 
of 32 mph. 

To determine rolling resistance, the Weasel was 
permitted to coast down Mount Castleguard (Figure 
30) and markers were thrown out at timed intervals. 
The distances and angles were measured, correlated 
with time intervals and the other known factors, and 
the rolling resistance measured. In light powder snow 
over crust and with the weight of the vehicle 3,838 
pounds, the rolling resistance was found to lie 504 
pounds at 2 mph, 535 at 4, 627 at 8, and 730 at 16. 

Under some conditions, the minimum turning 
radius was as small as 12 feet, hut under most con¬ 
ditions, depending upon the speed and the terrain, 
it varied between 14 and 22 feet. 

In many other tests, the Weasel demonstrated its 
ability to negotiate a wide variety of terrain and bar¬ 
riers. Figure 31 shows it under way in deep fresh dry 
snow, and Figures 32 to 34 demonstrate the action of 
the flexible track in following contour. 








Figure 32. Pilot model of T-15 Weasel equipped with 3- 
inch chevron grousers for operations on the ice of the 
Saskatchewan Glacier. 


In a test of sidehill travel the Weasel successfully 
traversed a 16-degree slope at an angle of 3 degrees. 
On the level and up easy grades, it towed 16 skiers 
and hauled a sledge loaded to 2,000 pounds. 

It floats but has no motive power in water (Figure 
35). 

The Weasel is able to negotiate ditches with sides 
up to 50 degrees and steps of 12 to 15 inches, and to 
knock down green poplars or frozen conifers up to 
6 inches in diameter. A green 6-inch elm will bend 
and throw off a Weasel. Depending on the terrain, it 
can average 3 to 4 miles per gallon. 

In a tactical demonstration, a problem was organ¬ 
ized to determine the relative speeds of pursuing 
skiers and retreating Weasels over varied terrain. The 
skiers, supplied by the 87th Mountain Infantry Regi¬ 
ment, and the Weasels started at the same time, but 



Figure 33. Pilot model of T-15 Weasel equipped with 
production grouser and climbing a snow pinnacle. 


Figure 31. Operation in deep, fresh, dry snow indicates 
need for protecting engine of T-15 Weasel against “drown¬ 
ing” by snow. 





















130 


THE WEASEL 



Figure 34. Angular bogie wheels on the pilot model of 
T-15 Weasel closely follow track in negotiating moraine 
in Columbia Ice Fields. 


the skiers took off from a high ridge overlooking the 
vehicles. Despite the advantage of this schnss, they 
were unable to overtake the Weasels, which retreated 
to a predetermined strong point 2.9 miles away up a 
5- to 8-degree grade and arrived there 41 minutes 
ahead of the first pair of skiers (Figure 36). 

Comparative tests with the Aero-Sled, the Bombar¬ 
dier, the jeep with airplane tires, and the twin Archi¬ 
medean screw vehicle in 2 feet of partially consoli¬ 
dated powder snow showed that: (1) up a 1.4-degree 
slope, none of these vehicles can travel faster than 
the Weasel, with the Aero-Sled almost as fast; (2) 
down a 1.4-degree slope, the Weasel is second only 
to the Aero-Sled; (3) none of these vehicles can climb 
better than the Weasel; and (4) none of these vehicles 
can surpass the Weasel in sidehill traveling. 

The effect of the terrain on the performance of the 
Weasel is shown in Table 1, which gives the maxi¬ 
mum angle of climb, maximum speed on level, and 
average penetration of track for different surfaces. 



Figure 35. In water, pilot model of T-15 Weasel remains 
afloat but tracks give little net horizontal thrust or steer¬ 
ing control. 


Fable 1. T-15 Weasel Performance on Various Terrains.* 


Terrain 

Maximum 
angle of 
climb in 
degrees 

Maximum 
speed on 
level in 
mph 

Average 
penetra¬ 
tion of 
track 
in inches 

Hard ground. 

45-48 

32 

0 

Soft ground. 

(35) 

(30) 

(1) 

Frozen firn snow. 

32-36 

30 

0 

Spring firn snow. 

26-31 

15-20 

1-2 

Soft firn snow. 

15-18 

10-12 

3-6 

Snow with rain crust .... 

32-36 

30 

0 

Snow with sun crust .... 

(24-28) 

(15) 

(2) 

Snow with wind crust.... 

(20-24) 

(12) 

(3) 

Shallow powder (4-inch) on 
crust. 

20-24 

15-18 

2-5 

Deeper powder (10-inch) on 
crust. 

16-22 

10-12 

4-6 

Shallow powder (4-8 inches) . 

22-26 

12-16 

2-5 

Deeper powder (10-20 inches) 

10-14 

4-8 

6-12 

Deep wild snow (above 24 
inches). 

(0) 

(2-4) 

12-15 


* See report on snow studies in Chapter 18 of this volume. 
Values in parentheses ( ) are estimates interpolated from test 
data. 



4 1 




* 




V* - 

X 




wi 


'3 » 




Figure 36. Pilot models of T-15 Weasel outdistancing skiers in tactical test on Columbia Ice Fields. Even with the 
advantage of an 1,800-foot schuss from high ridge shown at upper right,skiers were beaten by 41 minutes over 2.9-mile 
test course. 





























T-15 WEASEL 


131 



Figure 37. C-54 taking oft at Wright Field, Dayton, Ohio, 
with T-15 Weasel secured for experimental parachute 
drop. 


In an attempt to study the possibilities of dropping 
the Weasel by parachute, one pilot model was 
dropped with a cluster of four parachutes from a 
C-54 cargo plane (Figures 37 to 39). The test did not 
succeed and the Weasel was seriously damaged, but 
further studies were made at Wright Field in coop¬ 
eration with the Army Air Forces, the Army Service 
Forces, and the manufacturer of the vehicle. Methods 
were devised for suspending either the T-15 or the 
M-29 (see below) Weasel from either the C-54 or the 
British Lancaster bomber. Numerous dropping tests 
were conducted with these vehicles protected by a 
specially developed non-rebound, shock-absorbing 
crash pad made primarily from corrugated cardboard 
similar to that used in “egg crate” packing and rein¬ 
forced with plywood web beams. In one series, six 
T-15 carriers were dropped and two were completely 
destroyed. In another series, fourteen drops were 
made from 1,000 to 2,000 feet with each vehicle 
weighing a total of 4,200 pounds; one of these units 
rolled over on its side and two rolled on their backs 
but all were driven away under their own power 
within 30 minutes. In still another series, four Weasels 
were dropped and only one casualty was reported—a 
unit which had previously been landed successfully 
seven times before. The method of securing these 
vehicles to the C-54 and the Lancaster, together with 
the special fairing developed, is shown in Figures 40 
to 43. The procedures to be employed in dropping 



Figure 38. T-15 Weasel dropping with cluster of four 
parachutes. 


the Weasel by parachute are described in a special 
publication. 20 

Production Model 

Long before the completion of these tests and the 
full appreciation of the failures they revealed, tool¬ 
ing was under way on the production models of the 
T-15 Weasel. Although the planned operation in 
Norway had been cancelled and some of the pressure 
removed from this project, the first production mod¬ 
els were completed in 205 days—25 days behind the 
date originally demanded by the Army to meet the 



Figure 39. T-15 Weasel landed, seriously damaged after 
experimental parachute drop. 


A— 















132 


THE WEASEL 



Figure 40. New fairing developed for dropping T-15 
Weasel by parachute. 



Figure 42. British Lancaster bomber carrying two T-15 
Weasels with new fairings and crash pads for parachute 
drop. 


schedule for the proposed Norwegian campaign. In 
some cases the design was slightly modified as a result 
of early test data, but in general the first models were 
built on the basis of avowedly incomplete informa¬ 
tion. Only a few of these production units were tised 
in combat theaters. 

5 3 THE M-29 (T-24) WEASEL 

5 - 31 Procedure 

As service records began to accumulate on the pro¬ 
duction pilot models of the T-15 and as these were 
compared with the test results obtained in the Co¬ 
lumbia Ice Fields trials, it became apparent that the 
Weasel might be improved and modified. Since its 
ground pressure is much less than that of wheeled or 
heavier track-laying vehicles, it seemed to offer par¬ 
ticular possibilities for use in swamps and mud, 
where these other vehicles cannot operate. Accord¬ 
ingly, a complete redesign was undertaken. 



Figure 41. New "egg crate" shock-absorbing crash pad 
developed for dropping T-15 Weasel by parachute. 



Figure 43. T-15 Weasel landed, undamaged and able to 
operate immediately under own power after drop with 
four-parachute cluster. New fairing and crash pad were 
used in this test. 

Among the major goals in this new design develop¬ 
ment were: (1) increased life, (2) reduced rolling re¬ 
sistance, (3) improved cooling to permit operation in 
the tropics, (4) increased flotation or effective area of 
track in contact with the ground, (5) improved spring 
suspension, (6) improved hill-climbing ability, and 
(7) increased cargo capacity. 

In order to increase the life of the Weasel, special 
attention was paid to using larger rivets in the track, 
strengthening the hull, improving the design of the 
front eyes of the front and rear springs, and develop¬ 
ing a new shaft and auxiliary bracket to prevent fail- 
tire of the track upper guide wheel and bracket. 

The original T-15 has several inherent character¬ 
istics of the track and suspension system which con¬ 
tribute to roughness in operation and a resultant 
high rolling resistance, and tend to reduce speed 
and acceleration. New types and sizes of tracks, 
plates, and grousers were investigated in an attempt 
to overcome these weaknesses. Different bogie wheel 
and sprocket assemblies were likewise tested. 































M-29 WEASEL 


133 



Figure 44. Front and side view of M-29 Weasel. 


Track width was increased up to 24 inches in order 
to increase the area in contact with the ground, and 
experimental models were tested for operation on 
hard ground and snow, and for hill-climbing ability. 

As a possible improvement in spring suspension, 
transverse springing was tried to give four points of 
support, a low rate spring, and reactions to vertical 
load which would be taken in the center of the hull, 
thus eliminating the inherent weaknesses of the out¬ 
rigger construction in the T-15 design. 

To improve hill-climbing ability, investigations 
were conducted on the advantages of moving the 
engine to place the center of gravity as far forward 
as possible, of increasing the power, of using a rear 
as against a front drive, and of changing the gear 
ratio combinations. 

Various hull arrangements were studied to give 
increased cargo space and to locate the accessory 
components more conveniently in the driver’s com¬ 
partment. 

Field tests on the redesigned vehicle began early in 
March 1943, and were conducted first at Kalkaska, 
Michigan, and later near Bow Summit, 28 miles 
north of Lake Louise, Alberta, Canada. 


5 - 3 - 2 Results 

Design 28 

The improvements resulting from the design study 
were incorporated in a model known as the T-24 
Weasel which later went into production under the 
identification of M-29 (Figures 44 to 46). As shown 
in Figure 47, it differs from its predecessor, the T-15, 
in having the engine in front and the track drive in 
the rear. Approximately all of the rear half of the 
watertight hull is clear space for cargo or special 
equipment, and seating is provided for three passen¬ 
gers plus the driver. 

Sixteen bogie wheels on each side carry the load. 
These are connected rigidly in pairs by forgings and 
are pivotally attached to the suspension. The vehicle 
itself is suspended on four semi-elliptic transverse 
springs with anchorages which are component parts 
of the hull framework. This construction reduces the 
tendency of the track to come off, distributes the load 
more uniformly over the track area by reducing the 
unit loading per bogie, and improves rolling re¬ 
sistance by shortening the unsupported track span 
between bogies. 














THE WEASEL 


134 



Figure 45. Top view of M-29 Weasel, showing 


The center of gravity is moved forward to 52 inches 
ahead of the center line of the sprocket, giving better 
load distribution on the track during climbing. 

Smaller sprockets, 12 instead of 18 inches in diame¬ 
ter as on the T-15, and smaller idlers make it possible 
to reduce the sponson height and to seat the driver 
and passengers over the track without increasing 
over-all height of the vehicle. 


? ....- 


The tread is increased to 45 inches, the track to 
20 inches, and the length of track on ground to 78 
inches, increasing the ground contact area to 3,125 
square inches, in contrast to 2,232 for the T-15. 

The over-all length of the hull is 119 inches, the 
width is 60 inches (65 inches including rub rails), and 
the height is 71 inches with the top up and 51 inches 
with both top and windshield down. Total gross 



Figure 10. Rear and side view of M-29 Weasel. 






























M-29C WEASEL 


135 


INSTRUMENT PANEL 


BULKHEAD, 


STEERING 

LEVERS 


DECK 

COAMING 



TRACK 


^CLUTCH 
HOUSING 

•TRANSMISSION 

Figure 47. Side elevation diagram of M-29 Weasel. 


DRIVE 

WHEEL 


weight, including a 1,200-pound payload, is about 
5,200 pounds, with a unit pressure at 1-inch penetra¬ 
tion of 1.7 psi. 

Performance 

Operating tests showed that the T-24 or M-29 
Weasel is faster, has less rolling resistance, can climb 
better, has lower fuel consumption, rides better, has 
larger cargo space, and performs better than does the 
T-15 or M-28 Weasel. 

Maximum speed, on a hard surface, as measured at 
an altitude of 3,000 feet, is 36.0 mph. Rolling resist¬ 
ance, as measured on the two models on gravel, is 
about 315 pounds at 2 mph, 320 at 4, 345 at 8, and 
400 at 16 for the M-29, as compared with about 370 
at 2, 420 at 4, 475 at 8, and 550 at 16 for the T-15. 

In one Lake Louise test for climbing ability in 
snow, an M-29 Weasel with a test weight of 3,950 
pounds successfully climbed a 24-degree hill in 8-inch 
powder snow over hard crust. Under the same condi¬ 
tions, a T-15 Weasel lost steering on a 16-degree hill 
and failed to climb the grade. In tests in 2 inches of 
fresh snow over 1/2 inch of crust over deep wet corn 
snow, an M-29 Weasel successfully climbed a 17-de¬ 


gree hill, while a T-15 failed and broke into the layer 
of corn snow. 

In general, under comparable conditions, the M- 
29 can climb about 20 per cent better in snow than 
can the T-15 and can travel about 12 per cent faster 
on hard ground. 

The track, which in the T-15 has a specified life of 
only about 10 miles on a hard surface, gives from 
1,000 to 2,000 miles of service in the M-29. (This was 
increased to 3,000 miles by July 1945.) 

Production Model 

The M-29 went into production on August 30, 
1943, with an original order of 1,000 units. This was 
later increased to a total of 4,102 by May 25, 1944. 

5 4 THE M-29C WEASEL (ARK) f 

541 Procedure 

In addition to using the Weasel on dry land, snow, 
and mud, it soon became desirable to convert it into 
a self-propelled, amphibious unit which could oper- 


f Projects OD-65, AC-60. 









































































































































136 


THE WEASEL 



Figure 48. Equipped with outboard motor, M-29 Weasel 
floats in water and achieves speed of 1.5 mph. 


ate in deep water, and which could be used for the 
rescue of airplane crews forced down in jungles, 
swamps, mud flats, and other inaccessible areas.s 
In April 1943, a standard M-29 Weasel was tested 
in a lake and performed quite unsatisfactorily. Its 
maximum speed was found to be about 1.5 mph, and 
it was totally unresponsive to steering by differential 
track speed. Detachable outboard motors were then 
investigated both as auxiliary and as primary means 
of propulsion (Figure 48), but these were abandoned 
because they increased the speed only to about 2.3 


g This phase of the investigation teas conducted by The 
Studebaker Corporation, South Bend, Inch, under OSRD con¬ 
tract OEMsr-1166, in cooperation with Sparkman & Stephens, 
Inc., New York, N. Y., under OSRD contract OEMsr-154. 



Figure 49. M-29 Weasel equipped with experimental 
track skirting for study of water propulsion by sub¬ 
merged tracks. 


mph, they were easily fouled by weeds, and they 
could not be readily stowed during land operations 
without seriously reducing cargo space. 

The preliminary tests had indicated that although 
the vehicle itself was not propelled at any great speed 
by tracks alone, the tracks apparently moved con¬ 
siderable amounts of water. This confirmed the be¬ 
lief that the low vehicle speed was due to opposing 
thrusts of the propelling and return track discharges. 
Track skirting and false bow and stern assemblies 
were therefore installed for an investigation of mini¬ 
mizing the return track thrust. The skirts and baffles 
were arranged to reduce the inflow of water to the 
return track, and the baffles were arranged in the false 
bow structure to cause the discharge jet to impinge on 
the shrouding forward of the track and thus regain in 



Figure 50. Side view of M-29C Weasel, with rudders lifted. 




























M-29 WEASEL 


137 



Figure 51. Side and rear view of M-29C Weasel, with rud¬ 
ders lifted and top up. 


the form of a forward thrust some of the energy lost 
in the return track. 

The experimental unit (Figure 49) was tested in 
water and gave a speed of about 3.3 mph. The track 
could not be run at maximum speed because the 
volume of water pumped by the return track, to¬ 
gether with the discharge velocity impinging on the 
bow skirt, was directed upward and tended to swamp 
the vehicle. A critical lack of sufficient freeboard was 
self-evident. Steering, however, was greatly improved. 
No increase in weed-fouling was noticed, and the 8- 



Ficure 52. Side and front view of M-29C Weasel, with 
top up. 

inch clearance provided by the skirt did not detract 
from normal cross-country performance. 

It was tentatively concluded that (1) a completely 
submerged track could be used as the sole means of 
propulsion, (2) a maximum water speed of 4.0 to 
4.5 mph could be expected with properly designed 
equipment, and (3) bow and stern tanks are necessary 
to increase freeboard and to increase the propulsive 
force of the water moved by the track. 

Bow and stern cells and side skirts were then de¬ 
signed and constructed primarily as a subassembly 



Figure 53. Top view of M-29C Weasel, showing bow and stern cells, capstan, twin rudders lowered into place, and 
accommodations for driver and three passengers. 









138 


THE WEASEL 



Figure 54. Instrument board and controls in driver’s 
compartment of M-29C Weasel. 


which could be installed in the field. The lower por¬ 
tion of the bow cell, on which the return track dis¬ 
charge impinges, was shaped in the form of a Pelton 


cup, directing the discharge water downward and 
rearward. Compound vanes were also added to the 
discharge section of the bow cell and arranged to 
discharge a portion of the return track water out¬ 
board and rearward. T his arrangement tends to re¬ 
verse the direction of return track discharge, thus 
producing a forward thrust on the vehicle. 

The triangular stern section was mounted so that 
the bottom edge of the stern sheet was tangent to the 
track and could act as a stripper, baffling part of the 
slip-stream away from the return track chamber. The 
side skirts were made removable and designed to give 
1-inch clearance at the track edge. In addition, a re¬ 
movable baffle extending outward from the hull bot¬ 
tom was installed to prevent recirculation of water 
between the upper and lower tracks. Provision was 
made for installing a wood spar or filler in the return 
track section between the inside edge of the track and 
the side of the hull center section immediately below 
the sponson floor. The installation of the filler block 
confined the return track water and also gave addi¬ 
tional buoyancy. Later a bow modification was added 
to give greater bow buoyancy, added length of hull, 
and reduced water resistance. 

Various combinations of all these accessories were 
tested to explore the effect of increased discharge of 
the return track, track skirting, and additional buoy¬ 
ancy in the bow cell. These tests showed: 

1. Removal of the outside track skirting reduces 















M-29C WEASEL 


139 


maximum vehicle speed by approximately 33 per 
cent and also results in considerable loss of steering 
control. 

2. Inside track skirting, when applied as a horizon¬ 
tal baffle, does not materially affect speed, but the 
addition of a sponson tank indicates an increase of 
about 2 per cent in maximum speed. 

3. Increased area of discharge in the bow gives an 
increase in speed. 

4. Added length of hull obtained by bow shape 
gives a slight increase in speed. However, a departure 
from a scow bow to a sharper bow does not seem de¬ 
sirable in an amphibious vehicle because the former 
is preferable when the vehicle is operated in brush or 
jungle. 

Various rudder arrangements were tested for steer¬ 
ing response, with the best being two rudders, 


mounted as high as possible, which swing freely on 
hinges to prevent damage from rocks or logs, and 
which can be protected for land operations by lifting 
and stowing them on the deck. 

5 - 4 - 2 Results 

From the results of the studies came the design of 
the production model of the Ark or amphibious M- 
29C Weasel. Views of this model are shown in Fig¬ 
ures 50 to 56, with a longitudinal section and plan 
view given in Figure 57. 2 ’ 30 

This unit, like the nonamphibious M-29, has a 
front engine and rear track drive. It is larger than 
the nonamphibious unit, with an over-all hull length 
of 174 inches, an over-all hull width of 60 inches, and 
an over-all height with top and windshield up of 71 



BOW HATCH 
COVER 



Figure 57. Flan and elevation diagram of M-29C Weasel. 























































































































































140 


THE WEASEL 


Table 2. Comparison of Weasel Models. 


Second 

First pilot model 

pilot model (non- 



(amphibious) 

amphibious) 

T-15 

M-29 

M-29C 

Over-all hull length, without pintle hook, in inches . 

196 

132 

132 

119 

174 

Over-all hull width in inches. 

60 

60 

60 

60 

60 

Height, top and windshield down, in inches. 

50.5 

49 

49 

51 

51 

Height, top and windshield up, in inches. 

67 

67 

67 

71 

71 

Weight light in pounds. 

. 5,800 

3,200 

3,400 

4,000 

4,800 

Payload in pounds. 

1,200 

1,200 

1,200 

1.200 

1,200 

Weight loaded in pounds. 

. 7,000 

4,400 

4,600 

5,200 

6,000 

Track width in inches. 

15 

18 

18 

20 

20 

Length of track on ground in inches. 

89 

60 

62 

78 

78 

Tread in inches. 

45 

42 

42 

45 

45 

L/T. 

1.97 

1.6 

1.48 

1.73 

1.73 

Ground contact area for zero penetration, in square inches 

. 2,670 

2,160 

9 232 

3,125 

3,125 

Unit ground pressure for zero penetration, in psi . 

2.62 

2.02 

2.06 

1.56 

1.91 

Ground clearance in inches. 

12 

12 

12 

11 

11 

Cargo floor area in square feet. 


7 

7 

20 

20 

Cargo space volume in cubic feet. 


16 

16 

30 

30 

Center of gravity above ground, loaded, in inches . 

Center of gravity ahead of sprocket center line, loaded, 


20 

22 

24 

24 

in inches . 


46 

46* 

52 

52 

Angle of approach in degrees. 


60 

60 

90 

47 

Angle of departure in degrees. 


70 

70 

60 

36 

Maximum speed on land at sea-level, in mph . . .. 


33 

32 

36 

36 

Maximum speed in water, in mph. 

1.5 

t 

t 

t 

4 

Grade ability on hard surface, in degrees. 


45 

45 

45 

45 

Horsepower per ton gross weight at 3,000-foot elevation 

15.7 

24.7 

23.6 

21.1 

18.3 


* Ahead of idler center line, 
f Indeterminate and negligible. 


inches and with top and windshield down of 51 
inches. Total gross weight, including 1,200-pound 
payload, is about 6,000 pounds. 

At zero penetration, with a track width of 20 
inches, the unit pressure is 1.9 psi. The center of 
gravity is about 24 inches above the ground and 52 
inches forward of the center line of the rear sprocket. 
The ground clearance is 11 inches. 

Performance tests showed that the M-29C can 
achieve a speed of 4 mph in water and 36.0 mph on 
land, and can negotiate snow, mud, and other bar¬ 
riers as well as can any of its predecessors. It was 
operated by both civilian and military personnel in 
field tests in deep and shallow water, sand, surf, 
swamp, marshes, rice fields, snow, hard ground, and 
in areas overgrown with weeds and marsh grass, and 
in climbing and traversing snow-covered hills and 
muddy banks. 

Further tests indicated the M-29C would probably 
be useful for carrying personnel, pack howitzers, mor¬ 
tars, stores, and ammunition, for evacuating casual¬ 
ties, for reconnaissance in difficult terrain, for towing 
small trailers or guns, and for laying wire. 


Production Model 

The M-29C went into production on May 25, 1944, 
with an original order of 3,400 units. This was later 
increased to a total order of 19,619 by April 25, 1945. 

5 5 MILITARY USE 

5,5,1 T-15 Weasel 

With the abandonment of the proposed operations 
in Norway, the T-15 was used in only one significant 
campaign—the reconquest of Kiska in the Aleutian 
Islands. Although this was technically the “frozen 
north” for which the T-15 had been developed, the 
vehicle was actually used not on snow but on hard, 
rocky beaches which the tracks and other structures 
were unable to survive, and on soft, deep tundra 
which it negotiated very well, although all wheeled 
vehicles w'ere mired. 

The T-15 was also used for training purposes, par¬ 
ticularly at the AAF Arctic Training Center in Colo¬ 
rado (Figure 58), where it was employed by men later 
assigned to ground patrol and rescue work along 
arctic air routes. 





























MILITARY USE 


HI 



Figure 58. T-I5 Weasel as used at AAF Arctic Training 
Center, Colorado, with solid cab top for winter operations. 


5 - 5 - 2 M-29 Weasel 

The second model of die Weasel, die M-29, was 
found to be a more rugged and more valuable vehi¬ 
cle. It was tested in training centers in the United 
States (Figures 59 to 61), and adopted by a special 
British scouting group training in Canada as the only 
motorized vehicle which could negotiate the Banff- 
Lake Louise area in winter. In the northern United 
States, Canada, and Alaska, it was used by the Air 
Transport Command to make possible efficient 



Figure 59. Like its predecessor, M-29 Weasel can negoti¬ 
ate steep grades both uphill and downhill. 


ground transportation, and patrol and rescue work 
during winter along the U. S.—Siberia air route. 

In Europe, the M-29 made its first appearance at 
the crossing of the Rapido River in Italy where it was 
used for hauling ammunition across the muddy ap¬ 
proaches to the river. Later it was used on the Anzio 



Figure 60. At Camp Hale, Colorado, M-29 Weasel (with trailer) serves for training and for transportation in winter. 








142 


THE WEASEL 






Figure 63. Near Roer River in Germany, a 9th Army M-29 Weasel fills its major role: evacuating casualties. 


Figure 61. Training Arms personnel to operate M-29 Weasel with guide lines attached to controls, a procedure devel¬ 
oped originalh for use in the vicinity of crevasses and later used in the European I heater for reconnaissance through 
mine fields. 













MILITARY USE 



Figure 64. M-29 Weasel gets through mud at Ordnance Field Depot in France. 

beachhead to rescue 2i/9-ton trucks mired in the Ital¬ 
ian mud, and in the assault on Mount Gassino. In the 
invasion of France, it was used in the first D-Day land¬ 
ings at Utah Beach in Normandy. 

As one of the very few vehicles which could operate 
satisfactorily in snow, the M-29 found extensive use 
during the winter campaigns in Italy, France, and 
Germany (Figure 62). Medical units reported that 
while slippery roads and snow-drifted fields often 
stopped jeeps, trucks, half-tracks, and even tanks 
which were pressed into service, the Weasel was the 
only vehicle which coidd get through without bog¬ 
ging down and causing loss of time and lives. Snow 
drifts 4 or more feet high and even mines buried in 
frozen ground failed to stop it, its ground pressure 
not being great enough to detonate the mines. 

In mud, swamps, and shallow water, however, the 
Weasel appeared to its best advantage (Figures 63 to 
65). Some units used the M-29 to supply detached 
posts which could not be reached by any other vehi¬ 
cle. Others used it in shallow water to move supplies 
and evacuate wounded. It was widely used for wire¬ 
laying operations by the Signal Corps, as well as for 
reconnaissance, message carrying, and occasional 
emergency transportation of personnel. 

In one operation in the Hiirtgen Forest, where it 
was believed that no motor vehicle could negotiate 

cSSSSSSSeu 


the terrain and only horses could get through, the 
failure of necessary pack saddles to arrive made it 
essential for the Weasel to attempt evacuation of 
casualties. The Weasel was found to perform com¬ 
pletely satisfactorily. 

In other areas the Weasel was used in mine fields 
for the detonation of anti-personnel mines. Ecpiipped 
with rollers in front of each track and additional 



Figure 65. A flooded road in Germany provides sufficient 
traction for an M-29 Weasel. 























144 


THE WEASEL 



Figure 66 . M-29 Weasel brings in prisoners on hard road 
in Normandy (harder on Weasel than on prisoners). 

rollers towed to cover the area between the tracks, 
the vehicle was remotely controlled by operators 
walking 20 or 30 yards behind and using light ropes 
attached to the steering levers as “reins.” 

The M-29 made its least auspicious showing in 


Normandy, where it was driven on harcl-surfaced 
roads in the hedgerow country (Figures 66 and 67). 
In spite of the fact that the vehicle was not designed 
for this type of operation, having a design life of 
only a few hundred miles on hard roads, it was used 
until the tracks fell off—in some cases more than 900 
miles. 

Reports from the Pacific and China-Burma-India 
theaters also indicated the value ot this vehicle, par¬ 
ticularly for evacuation of casualties and wire-laying 
operations over terrain impassable to wheeled vehi¬ 
cles and to heavier track-laying units. The M-29 
proved so useful in evacuating casualties across the 
swamps and rice paddies of Leyte and Okinawa that 
the Army and Marine medical groups rarely had suf¬ 
ficient Weasels on hand to meet the requirements. At 
Iwo Jima, its performance over soft volcanic dust 
made it invaluable for evacuation of wounded per¬ 
sonnel and general cargo carrying, and it was often 
the only vehicle of any kind which coidd get over 
this type of ground. At Saipan, Guam, Tinian, 
Kwajalein, Bougainville, Luzon, and Mindanao, the 



Figure 67. M-29 Weasels used as troop carriers in break-through at Saint Lo. 









MILITARY USE 


145 



Figure 68 . In field tests on Roosevelt Island in Potomac 
River, the M-29C Weasel penetrates weedy marshes. 


Weasel was employed successfully over many types 
of terrain, although only in small numbers. 

Objections to the use of the M-29 included state¬ 
ments that it was too noisy, sounded like a tank, and 
therefore drew enemy fire, it was not protected by 
armor, and it could not climb every steep incline. 

5 - 5 - 3 The M-29C Weasel 

Field trials and demonstrations of the amphibious 
M-29C Weasel (Figures 68 to 70) quickly indicated 
the additional usefulness of this vehicle, notably as a 
litter carrier for evacuation of wounded over difficult 
terrain (Figure 71). 

Although it saw action in Europe (Figures 72 and 
73), particularly in the invasion of Walcheren Island 
and the crossing of the Rhine, it was in the Pacific 
that this amphibious model was applied most dra- 



Figure 70. This M-29C Weasel towing a 105-mm howitzer 
went through this Louisiana mudhole 18 times before be¬ 
coming mired. 



Figure 69. M-29C W easels operate successfully in swamps 
and bayous of Louisiana. 


matically. Like the M-29, the M-29C was used in small 
numbers at Mindanao, Kwajalein, Saipan, Guam, 
Tinian, and Burma, but at Iwo Jima, Leyte, and 
Okinawa it was employed in large fleets with excel¬ 
lent results. In the jungles of Bougainville and the 
swamps, marshes, rice paddies, and river country of 
Leyte, Luzon, and Okinawa, it was employed where 
no other vehicles—often not even the nonamphibious 
M-29—could operate (Figures 74 and 75). 



Figure 71. Special equipment makes M-29C Weasel useful 
for evacuating casualties over difficult terrain. 











146 


THE WEASEL 



Figure 72. British-manned M-29C Weasels and LVTs land on Walcheren Island in assault on Antwerp. 


On Bougainville, although only limited numbers 
of the M-29C were available, these units demon¬ 
strated their versatility by carrying men and sup¬ 
plies through jungles, mud, sand, and water where 
no other single vehicle could do the job, and even by 
towing guns through obstacles which hopelessly 
mired other vehicles (Figure 76). 

As with the M-29 in Europe, the M-29C Weasel in 
the Pacific was peculiarly suited for wire-laying over 
terrain in which a single vehicle often had to nego¬ 


tiate mud, water, and stretches of hard roads. Since 
it could cover terrain inaccessible to any wheeled 
vehicle and since it could be adequately water¬ 
proofed and blacked-out for night operation, it was 
widely used as a mount for vehicular radios, carrying 
the necessary equipment for a three-man radio team 
which would otherwise require a ^-ton, 4x4 truck 
plus a trailer. 

On Leyte, it was reported that the M-29C was the 
most valuable of all cargo carriers, and that it was 








MILITARY USE 


147 




Figure 75. 


M-29C Weasel with amphibious trailer gets through deep water in Solomon Islands. 

















148 


THE WEASEL 




was the only vehicle which could operate in the cross¬ 
country maneuvers which characterized a large part 
of the campaign; it consistently negotiated rivers, rice 
fields, swamps, mud, and sand without difficulty, and 
even operated for extended periods on roads and 
other hard surfaces. Because of the nature of the 
campaign, the extensive zone of division supply re¬ 
sponsibility, the heavy rainfall, the extremely rough 
and almost impassable terrain, and the limited road 
network, Army officials constantly called for more 
adequate quantities. The commanding general of 
one infantry division asserted that 200 to 225 M-29C’s 
would be desirable for a division operating in similar 
terrain. 

In some cases, reports pointed to the virtual free¬ 
dom of the M-29C from failure and breakdown, and 
one division stated that with 103 units distributed 
throughout its medical, communications, and trans¬ 
portation groups and seldom at rest, never were more 
than five vehicles laid up for repairs at any one time. 
In other cases, it was reported that the Weasel suf¬ 
fered from delicate mechanical construction which 
required extreme care in operation and close first 
echelon maintenance, with excessive track failure 
noted after about 450 to 500 miles. In still others, 
it was reported that Weasels were often inoperative 
for excessive periods because of the lack of spare 
parts. 

The Weasel was used to greatest advantage in the 
later campaigns, culminating in Okinawa. Drivers 
and maintenance personnel improved the perform¬ 
ance of the M-29C by developing numerous field 
expedients, such as getting across extremely soft, 
muddy obstacles by going in reverse, and folding up 
the track aprons to prevent damage or fouling when 
crossing rough or stony ground or swamp land. In a 
few instances, operators obtained maximum per¬ 
formance by discovering for themselves the wisdom 
of following the manufacturer’s instructions, notably 
using the lowest speed to cross very soft ground. 

As with other vehicles used in the tropics, the M- 
29C was criticized for inefficient cooling and exces¬ 
sive corrosion, and—as with other vehicles—the Weasel 
was improved by field changes developed in general 
engine and anti-corrosion research. 

Track failure was reported as the most serious fail¬ 
ure of all models of the Weasel. These failures, as 
reported from the field, led to intensive research and 
development which resulted in improved track de¬ 
sign and construction, as well as instructions to limit 


Figure 76. A mudhole on Bougainville is no different 
from one in Louisiana to M-29C Weasel. 

improbable that combat, movement, and evacuation 
could have been sustained without it (Figure 77). It 


Figure 77. In conquest of muddy Philippines, M-29C 
Weasel was a link in logistic chain from ships to DUKWs 
to forward mortar batteries in hills. 








CONCLUSIONS AND RECOMMENDATIONS 


149 


the use of the Weasel on hard surfaces. Track life was 
consequently extended considerably beyond the early 
1,000-mile mark, and in such later operations as the 
resurvey of the Alcan and Norman Wells highways in 
Alaska and Canada during the winter of 1944-45, 
tracks survived more than 3,000 miles without failure. 

56 PRODUCTION SUMMARY 

The performance of the Weasel, its ability to oper¬ 
ate in mud, swamps, paddy fields, marshes, snow, 
shallow and deep water, and on turf and hard roads, 
and its value in transporting men and supplies under 
conditions where no other vehicle could operate all 
resulted in a total production of approximately 
12,000 units by the end of the war, including about 
750 T-15’s, 3,000 M-29’s, and 8,000 M-29C’s. Plans for 
invasion of the Japanese home islands, the China 
coast, and other enemy-occupied territories included 
the production of about 10,000 additional M-29C’s, 
which were on order on the date of Japanese 
surrender. 

5 7 CONCLUSIONS AND 

RECOMMENDATIONS 

It appears that there will be a continuing need for 
amphibious vehicles able to traverse snow, mud, 
sand, and hard ground, and to operate in deep water. 
For the development of such vehicles, the following 
recommendations are offered: 

1. Development of the Weasel-type vehicle should 
be continued in order to develop both a small vehicle 
for reconnaissance work and a much larger vehicle, 
with a payload capacity of approximately l]/ 2 tons, 
for cargo carrying. 

2. The production designs of the T-15, M-29, and 
M-29C vehicles and their resultant highly satisfac¬ 
tory performance characteristics in soft terrain were 
achieved by construction and by quantitative tests of 
many variations in the several related units of the sus¬ 
pension and track system. Because of the urgency of 
the program, there was not time for a complete quan¬ 
titative evaluation of the test results. It is believed 
certain that some of the features of construction are 
fundamental factors in the performance of vehicles 
with low unit ground pressure, and it is believed de¬ 
sirable that these features should be more carefully 
examined. A long-range research program should be 
instituted for their thorough investigation and for 



Figure 78. United States Marines on Okinawa string tele¬ 
phone wire with aid of M-29C Weasel. 


the determination of fundamental equations for use 
in future designs of the vehicle type, regardless of 
size. Major emphasis in such a program should be 
placed on such factors as length-width ratios of tracks 
and track plates, heights of grousers, diameter and 
spacing of bogie wheels, angles of approach and de¬ 
parture, effect of ground clearance, finishes for tracks 
and underbodies to prevent sticking of ice and mud, 
and prevention of excessive accumulation of foreign 
matter in the suspension parts. 

3. Attention should be paid to facilitating loading 
and unloading the vehicles, particularly the M-29 
and M-29C Weasels, increasing their maneuverabil¬ 
ity while afloat, and increasing water speed. It ap¬ 
pears that the incorporation of a propeller for water 
propulsion is not desirable, and studies should there¬ 
fore be continued in an attempt to increase water 
speed from track propulsion and to increase ease of 
steering. 

4. The hull of the present M-29C should be rede¬ 
signed to reduce water resistance. At the same time 
the hull should be made in one piece instead of the 
three used in the current M-29C hull model, in order 
to reduce the weight materially without reducing the 
strength, and studies should be conducted on the 
proper angles of approach and departure for both 
the hull and the track. 

5. Further studies should be undertaken to reduce 
the weight and ground pressure of the vehicle. 

6. If the vehicle is to be used in any kind of surf, it 











150 


THE WEASEL 


will be necessary to increase the freeboard, water¬ 
proof the engine, and add power-driven bilge pumps. 

7. A lubrication system should be designed to re¬ 
duce the number of grease fittings in the bogie wheels 
and other suspension parts which require frequent 
attention, especially after water operation. In the cur¬ 


rent models, there are 58 such fittings. A system which 
would eliminate some of these or, perhaps, reduce the 
entire setup to a two-shot system would greatly reduce 
the driver’s responsibility during combat. 

8 . Further studies, including the use of a torque con¬ 
verter, should be made to improve transmission life. 





Chapter 6 

AMPHIBIOUS GUN MOTOR CARRIAGE 


Summary 

An amphibious combat vehicle/ based on the stand- 
ard M-18 gun carriage, was developed for use in 
landing operations. It is self-propelled, using its own 
tracks for water propulsion, and can fire either ashore 
or afloat. Three different models were designed and 
studied. 

61 THE PROBLEM 

Late in 1943, at the request of the U. S. Army Ord¬ 
nance Department, a study was under way on the con¬ 
version of the M-18 “Hell Cat - ’ 76-mm gun motor car¬ 
riage (Figure 1) into an amphibious vehicle. Instead 
of merely fitting pontons to the existing gun carriage, 
modifications were to be developed so that the M-18 
would be actually amphibious. The modifications, 
however, were to be kept to a minimum, and the 
standard components and their arrangements in the 
carriage were to be retained wherever possible/ 

62 PROCEDURE 

In order to facilitate production and repair, it was 
decided to use the M-18 engine, power train, suspen¬ 
sion, turret, and controls, all arranged as they are in 
the M-18 nonamphibious model. One pilot model 
(T-86) was designed to be track-propelled, a second 
(T-86E1) to be propelled by twin screw propellers. 

The design development included a study of im¬ 
proved tracks for the T-86 to give maximum water 

a Project OD-95. 



Figure 1. M-18 “Hell Cat’’ 76-mm gun motor carriage, 
parent vehicle for conversion. 


speed and ease in steering. Low freeboard, resulting 
from attempts to reduce the profile height to a mini¬ 
mum, and the necessity of providing full ends in the 
amphibious hull introduced vision problems, and 
various vision cupolas, periscopes, and block arrange¬ 
ments were tested in an attempt to solve them. Since 
steering by track was found to be unsatisfactory, 
cable-controlled rudders were added, and were found 
effective in both the T-86 and the T-86E1. Two air 
inlets were provided, one the conventional deck grill 
placed behind the turret, and the other through the 
turret cover to take all cooling air. Various types of 
cooling air exhaust stacks were tried. Field kit water¬ 
proofing was used in the first two models, but was 
not found satisfactory. 

At the conclusion of the design study and field 
tests, plans were begun for a third model, the T-87, 
which was to be the prototype of the production 
model and to contain many of the improvements de¬ 
veloped during this study. 5 

63 RESULTS 

631 Model T-86 

The track-propelled T-86 is shown in Figures 2 
and 3. It is 351 inches long, 122 inches wide, and 115 
inches high, with a ground clearance of 141/4 inches. 
Mounting a 76-mm gun and fully equipped, it weighs 
45,000 pounds and has provisions for a five-man crew. 
The track is 21 inches wide, giving a ground contact 

t> This investigation was conducted by Sparkman & Stephens, 
Inc., New York, N. Y., under OSRD contract OEMsr-154. 



Figure 2. Side and rear view of pilot model, T-86 am¬ 
phibious gun motor carriage. 


151 








152 


AMPHIBIOUS GUN MOTOR CARRIAGE 



Figure 3. Side view of pilot model, T-86 amphibious gun motor carriage, showing side track skirting. 


area at 4-inch penetration of 5,680 square inches and 
a unit ground pressure of 7.92. (See Table 1.) 


Table 1. Comparison of Amphibious Gun Carriage Models. 



T-86 

T-86E1 

T-87 

Water propulsion 

Tracks 

Propellers 

Tracks 

Over-all hull length in inches 

351 

351 

324 

Over-all hull width in inches 

122 

122 

122 

Height in inches 

115 

115 

115 

Weight in pounds 

45,000 

46,000 

45,000 

Track width in inches 

21 

21 

21 

Length of track on ground 
in inches 

117 

117 

117 

Tread in inches 

95 

95 

95 

Ground contact area in square 
inches 

5,680 

5,680 

5,680 

Unit ground pressure for 1-inch 

penetration (psi) 

7.9 

8.2 

7.9 

Ground clearance in inches 

14 

14 

14 

Angle of approach in degrees 

31 

31 

31 

Angle of departure in degrees 

35 

38 

40 

Maximum speed on land (mph) 

45 

45 

45 

Maximum speed in water (mph) 

5.2 

6.2 

5.4 

Grade ability in per cent 

60 

(iO 

60 

Horsepower per ton load 

15.5 

17.4 

17.8 


Its maximum speed is 45 mph on land and 5.2 mph 
in water, its cruising range is 150 miles on land and 
30 miles in water, and it can be operated in a 12- to 
16-foot surf. 

In sea trials at Fort Old, California, and Rehobeth 
Beach, Delaware, maneuverability and control were 
both satisfactory, and pitching and rolling were not 


severe enough to interfere with the comfort and 
safety of the crew. Except for small seal leaks, the 
crew and equipment were satisfactorily protected 
from waves and splash. The vehicle was run through 
surf ranging in height from 3 to 10 feet without seri¬ 
ous diving or pitching. Performance in sand and on 
beaches was considered satisfactory, and the vehicle 
was able to land on the beach from the water at all 
points in the test areas. 

Operation both in water and on land was im¬ 
proved by adding a third steering station just for¬ 
ward of the turret, cutting off the forward corners of 
the deck trunk, installing a vision block in both cor¬ 
ners, and substituting a vision block for the forward 
periscope on the driver’s side. 

In one firing test, the vehicle opened fire at 1,500 
yards and ran in to 800 yards, firing about 20 rounds. 
The accuracy was extremely poor, with all but the 
first shot going high. In another test, the vehicle 
opened fire at 2,300 yards and hit the target with four 
shots. Military observers indicated that the difference 
in these results was due to the difference in experi¬ 
ence of the gun crews. 

6 - 3 - 2 Model T-86E1 

I he propeller-equipped I -86E1, as shown in Fig¬ 
ures 4 to 6, differs from the T-86 in having a total 
gross weight of 46,000 pounds, a unit ground pres¬ 
sure of 8.22 psi, a maximum speed of 6.2 mph in 
water, and a cruising range of 150 to 175 miles on 
land and 60 to 85 miles in water. 

















RESULTS 


153 



Figure 4. Side view of pilot model T-86E1 amphibious gun motor carriage. 



Figure 5. Twin propellers on T-86E1 (Modification 1) 
amphibious gun motor carriage. 



Figure 6 . T-86E1 amphibious gun motor carriage afloat. 



Figure 7. Pilot model of T-87 amphibious gun motor 
carriage. 


6 3 3 Model T-87 

Although the addition of propellers to the gun car¬ 
riage increases the speed and the cruising range of 
the vehicle, the added equipment increases the total 
weight to 46,000 pounds. Accordingly, the prototype 
model T-87, shown in Figures 7 and 8, was designed 
to meet the specification of 45,000 pounds. Driven by 
tracks like the T-86, it differs from the former in 
having a hull length of only about 27 feet, factory 
waterproofing, and different armament, including a 
105-mm howitzer, twin .30-caliber machine guns, and 
four automatic pistols. In water, its maximum speed 
is expected to be 5.4 mph and its cruising range 40 
miles. 

Design work on this model was started under 
NDRC, but final design and construction was done 
under the Development Branch, OCOD. 

Another design was completed as the result of a 
study of a larger amphibian built from standard com¬ 
ponents but not using a standard chassis as a basis. 
Intended to incorporate desirable features without 
concern for the time limitation in building pilot 
models, it follows the recommended trend in new 
amphibious tank design. The rear drive permits the 
turret to be moved forward. A sixth bogie is added 
to increase ground contact area and decrease unit 
ground pressure. 
















154 


AMPHIBIOUS GUN MOTOR CARRIAGE 




Figure 8. Diagram of T-87 amphibious gun motor carriage. 








































































































Chapter 7 

PADDY VEHICLE 


Summary 

light amphibious cargo carrier with a low unit 
ground pressure was designed for use in rice 
paddies and similar water-covered areas.' 1 Based on 
the T-39 light tractor, a pilot model of this paddy 
vehicle was constructed for field tests under the Ord¬ 
nance Department. 

? 1 THE PROBLEM 

In answer to a need expressed by the U. S. Army 
Ordnance Department, a study was initiated in Sep¬ 
tember 1944 on the conversion of available track¬ 
laying vehicles into light amphibious cargo carriers. b 

7-2 PROCEDURE 

A survey and preliminary analysis was made of all 
available vehicles and components, together with ex¬ 
perimental models undergoing tests or still on the 
drawing boards. From this analysis, it appeared that 
the most promising vehicles which might be used as 
a basis for the new paddy vehicle were the T-16 uni¬ 
versal carrier, the T-9 light tractor, the T-9 light 
tank, the T-39 light tractor, and the power train of 
the M-3 or M-5 light tank. 

Further study showed that an amphibian based on 

a Project OD-95. 



Figure 1. Front and side view of T-39 light tractor, par¬ 
ent vehicle for conversion. 


the T-16 universal carrier would have the advantage 
of light weight and low unit ground pressure, but 
would require considerable rearrangement of the 
power train. The amphibian would closely resemble 
the Weasel light cargo carrier but would have a 
higher rated payload and greater horsepower. 

A carrier based on the T-9 light tractor would be 
promising in payload and power, but a complete 
rearrangement of components would be needed and 
a new suspension would have to be designed to ac¬ 
commodate a wider track. 

The use of the T-9 light tank was considered at first 
but rejected because it was not then in production 
and would require many changes in the conversion. 

A vehicle based on the M-3 or M-5 light tank power 
train would have high rated payload, high horse¬ 
power per ton, and reliable, proved components. On 
the other hand, it would also have high gross weight, 
and its components would have to be completely 
rearranged. 

From these considerations, it was decided to pro¬ 
ceed with an amphibian based on the T-39 light 
tractor (Figures 1 and 2). It was expected that such a 
vehicle would require only minor changes in arrange¬ 
ment of components. Although its horsepower would 
be low and its track was unproved, it would have 
high payload, low ground pressure, and a reliable 

b This investigation was conducted by Sparkman & Stephens, 
Inc., New York, N.Y., under OSRD contract OEMsr-154. 



Figure 2. Top and side view of T-39 light tractor. 





155 


















156 


PADDY VEHICLE 



Figure 3. Diagram of T-34 paddy vehicle. 







































































































PROCEDURE 


157 



Figure 4. Side view of T-34 paddy vehicle, showing side track skirting. 


power train. These advantages were thought to be of 
considerable value. 

73 RESULTS 

Design work was begun under the National De¬ 
fense Research Committee [NDRC], with final de¬ 
sign and construction undertaken under the Devel¬ 
opment Branch, Office of Chief of Ordnance, Detroit. 

The design of the amphibian as converted from 
the T-39 is shown in Figure 3, with the pilot model 2 
shown in Figures 4 and 5.° 

The paddy vehicle is 19 feet 4 inches long, 8 feet 


wide, and 6 feet high to the deck, with a track width 
of 19 inches and a unit ground pressure of 4.3 psi. 
Cargo volume is 120 cubic feet, the floor area being 
55 square feet, and the payload 3,000 pounds. The 
weight light is 14,000 pounds. 

Later, after the termination of the investigation 
under NDRC, field tests were conducted under the 
Ordnance Department. These showed that the maxi¬ 
mum speed is 4.0 mph in water and 20.0 on land, the 
grade ability is 60 per cent, and the horsepower per 
ton is 12.8. 

c Constructed by the Lima Locomotive Works, Inc., Lima, 
Ohio. 



Figure 5. Rear view of T-34 paddy vehicle, showing skirt¬ 
ing and rudders. 


















Chapter 8 

PROPOSED AMPHIBIOUS VEHICLES 


PELICAN 
Summary 

nder this project, a a survey was made of existing 
land vehicles and components available for use 
in large-wheeled and half-track amphibians to have 
a rated payload of 6 tons or more. Design and de¬ 
velopment extended only through drawings, calcula¬ 
tions, and scale model tests. No full-size pilots were 
constructed. 

811 The Problem 

By July 1942, early work on the DUKW 2 1 /£-ton 
amphibian indicated that a larger vehicle was desir¬ 
able, and a design study was consequently initiated 
for such a vehicle to be based on a standard land 
vehicle or its components. b 

812 Procedure 

As a basis for a wheeled amphibian with a 6-ton 
payload, several models were considered. 

a Project OD-95. 


White 6-Ton 6x6 Chassis 

Layouts were prepared and a scale model tested of 
a propeller-driven amphibian with a scow-type hull 
and wheel cutouts and tunnels similar to those in the 
DUKW. 

The full-size model would be about 34 feet long 
and 8 feet wide, and would weigh 28,000 pounds 
light. 

Brockway 6-Ton 6x6 Chassis 

Two scale models were built and tested, the first 
having a DUKW-type hull and the second having a 
boat-type hull with appendages, as shown in Figure 1. 

In full scale, each would be approximately 41 feet 
long and 10 feet wide and would weigh about 28,000 
pounds unloaded. 

Chevrolet Armored Car T-19 Chassis 

Preliminary layouts were made of a 5-ton 6x6 ve¬ 
hicle and a 7-ton 8x8 amphibian (Figure 2) based on 
the T-19 chassis. 

b This investigation was conducted by Sparkman & Stephens, 
Inc., New York. N. Y., under OSRD contract OEMsr-154. 






158 












































































PELICAN 


159 




The 5-ton amphibian has approximately the same 
over-all dimensions and weight light as does the pro¬ 
posed Brockway conversion, while the 7-ton vehicle 
is proportionately larger. Decreased resistance was 
anticipated because the power train would permit 
complete housing of the differentials and drive shafts. 
This chassis would have the advantage of more power 
than the Brockway, but it is not standard and was not 
in production at the time of the investigation. The 
time involved in getting such a vehicle in production 
was judged to be too long, and further work on it was 
dropped. 

These studies indicated that the preferred hull for 
wheeled cargo amphibians is essentially rectangular 
in section, with a scow bow, little or no dead rise, 
tunnels for all appendages, full scow stern, and maxi¬ 
mum housing for all wheels. 

Half-tracks 

For payloads more than 6 tons, the disadvantages 
of wheeled vehicles become decisive. Study was there¬ 
fore initiated on a series of half-track amphibians for 
payloads of from 2 to 25 tons. Calculations and lay¬ 
outs were made and some scale models tested. 

Only brief consideration was given to a proposed 
amphibian based on the standard Army troop-carry¬ 
ing half-track, which would have a gross weight of 
about 19,000 pounds but a rated payload of only 
about 4,000 pounds. 


Instead, major interest was devoted to a half-track 
amphibian based on the track and suspension of the 
medium tank. It was concluded that a practical half¬ 
track amphibian would require a completely new 
design. It would have to be appreciably larger than 
the DUKW and accordingly would have additional 
uses, such as ferrying a fully loaded 214 -ton truck in 
ship-to-shore operations. Since it was desirable to use 
existing equipment, the medium tank track and sus¬ 
pension apparently offered the best basis on which a 
new design might be started. 

Four primary designs were prepared, one with two 
individually suspended front wheels and two-thirds 
of the medium tank track and suspension (Figure 3), 
one with four front turning wheels and two-thirds of 
the track and suspension (Figure 4), and two designs, 
each with four wheels and full track and suspension 
(Figures 5 and 6 ). 

In each case both screw and Kirsten cycloidal 
propellers were studied. The proposed gross weights 
vary from 40,000 to 110,000 pounds, and the over-all 
lengths from 40 to 55 feet. The vehicles would be 
powered by two 220-hp Diesel or gasoline engines, 
and would incorporate a loading ramp to enable 
them to carry fully loaded trucks or tanks. 

Model tests showed that, in general, the front 
wheels account for about 6 per cent of the total resist¬ 
ance, the tracks for about 9 per cent, the front wheel 
cutout for about 10 per cent, the track cutout for 


















































































160 


PROPOSED AMPHIBIOUS VEHICLES 




Figure 3. Plans for proposed Pelican with two front wheels and two-thirds of medium tank track. 


about 15 per cent, and the combination of wheels and 
cutouts alone for about 50 per cent. It is apparent, 
therefore, that the pure hull efficiency is reduced by 
the necessity for housing wheels and other append¬ 
ages, and that the actual and incidental increase in 
resistance due to wheels, wheel suspension, and driv¬ 


ing equipment is at least as great as the resistance of 
a comparable boat. 

The lowest resistance per ton for the same speed- 
length ratio of all models tested is given by the ve¬ 
hicle with two front, individually suspended wheels 
and full medium tank track and suspension. A fnll- 




Figure 4. Plans for proposed Pelican with four front wheels and two-thirds of medium tank track. 

































































































































































































PELICAN 


161 



scale unit of this type (Figure 7) would have an over¬ 
all length of 51 feet and a width of 144 inches. With 
400 hp to drive two cycloidal propellers, it would 
have a speed of 8 mph in water. It would weigh 40,000 
pounds light and 80,000 pounds loaded. It would 
have a stern ramp and sufficient cargo space to take a 
fully loaded 6-ton 6x6 truck. 


8-1,3 Conclusions 

Although none of the units investigated in this 
study was carried to completion, the information ob¬ 
tained was applied to advantage in the study of other 
amphibious vehicles designed under Division 12 1 and 
should be of value to any future program for the 
design of amphibious cargo carriers. 



























































































































































































162 


PROPOSED AMPHIBIOUS VEHICLES 



Figure 7. Plans for final proposed Pelican with two front wheels and full medium tank track. 


8.2 FIFTEEN-TON, %-TRACK 

AMPHIBIOUS CARGO CARRIER 
Summary 

Designs have been developed for a 15-ton, ^-track 
amphibious vehicle to carry heavier loads and bigger 
vehicles than was previously possible. Drawings and 
model tests were completed, but no pilot model was 
built. 

8 21 The Problem 

At the request of the U. S. Army Ordnance Depart¬ 
ment, design work was undertaken in May 1944 on a 
large ^-track carrier for ship-to-shore operations. 0 

c This investigation was conducted by Sparkman & Stephens, 
Inc., New York, N.Y., under OSRD contract OEMsr-154, in co¬ 
operation with the Development Branch of the Office of Chief 
of Ordnance, Detroit, Mich. 


822 Procedure 

A study of existing U. S. Army half-tracks and cap¬ 
tured German ^-tracks, together with conferences 
with Ordnance Department representatives, led to 
the design shown in Figures 8, 9, and 10. Later, in 
order to provide closer coupling of track and front 
wheels, a sixth bogie wheel was added on each side, 
as shown in Figure 11. This also reduced the unit 
ground pressure by increasing track ground contact 
length and ground contact area. 

Individual suspension or a single transverse leaf 
spring suspension for the front wheels was recom¬ 
mended. This provides for a minimum of hull move¬ 
ment over uneven terrain. Size 14:00 by 24 tires were 
selected to improve mud performance. An intermit¬ 
tent front wheel drive was specified to assist in exits 
from the water by traction and to improve steering 



Figure 8. Side view of model of proposed 15-ton, -track amphibious cargo carrier. 


o 






























































































































CARGO CARRIER 


163 



Figure 9. Model of proposed 15-ton, y-track amphibious 
cargo carrier showing stern ramp down for unloading. 


control in surf or up steep banks or beaches. A 21- 
inch steel track as developed for the T-87 amphibious 
gun motor carriage was specified because its width 
and low weight contribute to low unit ground pres¬ 
sure and improved performance. Further track de¬ 
velopment was recommended. Torsion bar, volute 
spring-stopped suspension was specified especially be¬ 
cause these standard components were already in 
production. 

The M-18 power equipment was specified because 
of its availability and proved worth. An hydraulic- 
tvpe transmission was recommended to prevent dig¬ 
ging in water exits by gradual application of increased 
torque as required. 

A ramp was provided to assist loading and unload¬ 
ing of cargo and vehicles to be carried in the cargo 
space. Sufficient space was indicated to permit load¬ 


ing and transport of Army vehicles up to and in¬ 
cluding light tanks. 

8 - 2,3 Results 

The hull design as shown in Figure 10 was later 
modified to permit the vehicle to enter an LST 
[Landing Ship, Tank] ramp from the water. Wheels 
and tracks were housed in cutouts fitted with outside 
cover plates. A permanent cover plate and a removal 
plate were specified. A rectangular hull in cross sec¬ 
tion with no dead rise provides maximum buoyancy 
for given dimensions. Cutout cover plates for the 
tracks should be hinged to permit track servicing. 
Decking at the stern is necessary for protection in 
rough water and surf and in steep exits from water. 

A power take-off for a twin screw propeller drive is 
shown, with the propellers and rudder housed in a 
tunnel protected by the hull and the track. In case 
the propellers are damaged, emergency propulsion 
can be obtained from the shrouded track. A modified 
Kort Nozzle propeller shrouding 11 was incorporated. 

The proposed vehicle, as shown in Figure 11, would 
have a net weight of 40,000 pounds and a payload of 
30,000. Its estimated maximum land speed is 35 mph, 


(t Designed by the Dravo Corporation, Pittsburgh, Pa. 



Figure 10. Plan of proposed 15-ton, y -track amphibious cargo carrier. 















































































































164 


PROPOSED AMPHIBIOUS VEHICLES 



its water speed 8 mph, its land cruising range 200 
miles, and its grade ability 60 per cent. 0 

83 AMPHIBIOUS TRAILERS 

Summary 

Several trailers were designed for use with the 
DUKW and the Pelican, and one 2i/2-ton, two-wheel 
experimental unit was built and tested. 

8.3.1 The Problem 

In order to increase the carrying capacity of pro¬ 
posed amphibious vehicles, a design study was insti¬ 
tuted on amphibious trailers which could be used 
with the DUKW or with one of the types of Pelican 
under consideration. 13 

8.3.2 Procedure 

Two designs were developed for the DUKW, one a 
1 -ton and the other a 2 i/ 9 -ton trailer, each with two 
wheels. Two others were developed for the Pelican, 



Figure 12. 2i/2-ton amphibious trailer attached to DUKW 
for land operations. 


one a 10-ton and the other a 20-ton trailer, each with 
four wheels. 

83,3 Results 

An experimental pilot model of a DUKW trailer 
was constructed as shown in Figure 12. e Its over-all 
length is 176 inches, its width 96 inches, its height to 
deck 65 inches, and its weight light 2,000 pounds. 
Tests showed that this trailer is unsuitable for use in 
the surf and that it decreases the maximum water 
speed of the tractor DUKW by about 2 mph. While 
the trailer offers a convenient method for increasing 
the payload of the DUKW (Figure 13), the disadvan¬ 
tages were sufficient to halt further development. 

The investigation showed that the wheels and sus¬ 
pension must be housed to reduce water drag, and 
that the trailer must be designed to act as an addition 
to the tractor hull. Separation from the tractor allows 
an independent wave system to form and tends to 
increase greatly the total surface wave-making resist¬ 
ance of the combination. 1 


e Built by the Yellow Truck & Coach Co.. Pontiac, Mich. 



Figure 13. Loaded 2i/2-ton amphibious trailer towing 
astern of loaded DUKW. 









































Chapter 9 

AMPHIBIOUS DEVICES 


9-1 VEHICLE FLOTATION DEVICES 
Summary 

V arious devices for ferrying vehicles or temporar¬ 
ily converting them for amphibious operation 
were studied intermittently from April 1941 to early 
in 1945. In many cases, only calculations and design 
sketches were completed; in others, the work pro¬ 
gressed as far as scale model tests; and in still others, 
pilot models were built and tested, and a few devices 
went into production. These latter included the 
Ritchie T-6 and T-7 rigid pontons for medium and 
light tanks, respectively, which were developed by 
the Ordnance Department with members of Division 
12 serving as design consultants. The T-6 device was 
used successfully in landing operations at Okinawa. 

911 The Problem 

A study of methods to land tanks under conditions 
in which landing boats cotdd not be used was started 
in April 1941.“ An early exchange of data with British 
workers led to particular emphasis on designs of rigid 
plywood or metal side pontons, but these were tem¬ 
porarily dropped without tests and major attention 
was given to the use of the DUKW as a ferrying 
vehicle. 

Effective “dry ferry” and “wet ferry” devices were 
developed for enabling the DUKW to carry vehicles 

a This investigation was conducted by Sparkman & Stephens, 
Inc., New York, N. Y., under OSRD contract OEMsr-154. 


up to the weight of the medium tank. b These devices 
were never exploited beyond the experimental stage 
since better means for doing the same thing were de¬ 
veloped by the Armed Services. The investigation of 
flotation was later redirected to flotation devices as 
well as flotation vehicles, and emphasis was again 
placed on ponton studies and similar problems. Fur¬ 
ther impetus to this approach was given by the suc¬ 
cessful submerged track propulsion tests made on the 
Weasel in the summer of 1943, c which, with later 
tests, clearly indicated the potentialities of water pro¬ 
pulsion by means of fully submerged standard land 
tracks. 

9,1-2 Procedure 

The loosely coordinated studies of Division 12 and 
OCOD were integrated under the “Ritchie Project” 
in January 1944, and Division 12 was requested to act 
throughout this program as a consultant to the Ord¬ 
nance Department. Under this project, several de¬ 
vices for tank flotation were built and tested, includ¬ 
ing the following; 

1. The Hale Device, with collapsible side pontons 
inflated by tank engine exhaust gas, the entire unit 
propelled by screw propellers driven off the rear 
idlers. 

2. The Engineer Ponton Device, with the tank sus¬ 
pended between two pontons in a wet ferry and pro¬ 
pelled by outboard motors. 

b See Section 3.6.2. 

c See page 174. 



Figure 1. M-4 A1 medium tank equipped with Ritchie T-6 flotation device. 






165 










1G6 


AMPHIBIOUS DEVICES 



Figure 2. Front view of M-4 A1 medium tank equipped 
with Ritchie T-6 flotation device. 


3. DD and Yagow Devices, consisting of collapsible, 
vertical, canvas tank hull extensions, the unit pro¬ 
pelled by screw propellers driven oil the track sus¬ 
pension. 

4. BB or Ritchie T-6 and Ritchie T-7 Devices, de¬ 
scribed below. 

5. The Blankenship Device, using detachable, in¬ 
flatable bags to provide the necessary additional 
buoyancy. 

6 . DUKW ferrying devices, described elsewhere. b 

91,3 Results 

The Ritchie T-6 Flotation Device 

Figure 1 shows the Ritchie T-G device fitted to the 
M-4 A1 medium tank. In this installation, two large 
welded steel pontons are attached by pins to the for¬ 
ward end of the tank (Figures 2 and 3), two other 
large units are attached to the aft end, and four 
smaller units are attached on each side. The unit is 
propelled in the water by its shrouded fully sub¬ 
merged tracks. Tests conducted at Tacony, Pennsyl¬ 
vania, showed that this model can travel at about 4.2 
mph in water (Figure 4). This speed can be increased 



Figure 5. Scale model of Ritchie T-7 flotation device 
attached to M-18 gun motor carriage. 



Figure 3. Pontons in Ritchie T-6 flotation device are 
secured with removable pins. 



Figure 4. Ritchie T-6 flotation device afloat. 

to nearly 7 mph by the use of special grousers, but 
these make land maneuvering more difficult. 

The T-6 device, slightly modified and supplied 
with equipment to jettison the pontons, went into 
production for possible use in the invasion of Nor¬ 
mandy. Actually, however, it was first used in combat 
in the invasion of Okinawa, when 20 of these devices 
were employed by the Marine Corps, making it pos¬ 
sible to place 20 tanks on the beach without the need 
of special landing boats. The pontons were detached 
as soon as the tanks touched land, allowing the units 
to go into action immediately without exposing their 
crews to direct enemy fire. 

The Ritchie T-7 Flotation Device 

The Ritchie T-7 device, as illustrated by the scale 



Figure 6. Experimental installation of Ritchie T-7 flota¬ 
tion device on M-18 gun motor carriage. 






















VEHICLE FLOTATION DEVICES 


167 


model in Figure 5, consists of only two pontons, one 
attached to the forward end of the M-18 gun carriage 
and one attached to the after end. The tracks are 
shrouded for higher propulsive efficiencies in the 
water. At the completion of the model tests, a full-size 
unit was constructed and fitted to the M-18 carriage 
(Figure 6). In field trials, the maximum speed of this 
unit in water was found to be from 4.2 to 4.8 mph. 
Similar devices were applied to the M-24 and M-5 A1 
light tanks. 

Light Tank Flotation Devices 

Several methods and types of equipment for float¬ 
ing different light tank models were studied between 
April 1942 and January 1945. Among these were ver¬ 
tical hull extensions, side and end pontons, rigid and 
collapsible floats, and the use of amphibious vehicles 
or boats to make up the deficient buoyancy. Experi¬ 


ments with the Straussler collapsible hull device were 
considered to be unsuccessful. The recommended 
types are the end float devices with either rigid pon¬ 
tons (Figure 5) or collapsible pontons (Figure 7). 

The pontons in the latter case would consist of in¬ 
flatable, rubberized fabric bags housed in metal 
covers which would unfold in the water and protect 
the bags in the floating and stowed position. A rotary 
vane pump would be used to inflate the bags through 
individual air lines. Since the front and the rear pon¬ 
tons would each be composed of three bag sections, 
the failure of one bag or its destruction by gunfire 
would not result in total failure of the flotation. In 
operating this device, the forward ponton would first 
be swung from its stowed position aft and its beam 
clamped into a beam lock. Both forward and aft bags 
would then be inflated, and the vehicle would be 
ready to enter the water. When the tank leaves the 





Figure 7. Diagram of collapsible fabric pontons designed for M-4 light tank. 








































































































AMPHIBIOUS DEVICES 


168 


water, the beam would be released from the beam 
lock, the pontons deflated, and the forward ponton 
swung aft. As the forward ponton falls into its final 
position, it would hit a stop and force the aft ponton 
into its final stowed position. 3 

Rigid Pontons for the Jeep 

During the early development of the amphibious 
jeep, tests® were conducted simultaneously on rigid 
pontons' 1 to be attached to the sides of the standard 
GP l^-ton truck. These pontons swing down into 
the water from a stowed position and are to float the 
vehicle at a water line about 5 inches below the wheel 
hub center. Propulsion would be obtained from an 
outboard-drive screw propeller driven by a power 
take-off from the truck engine. Towing tank tests 
with scale models, however, showed that although 
these pontons permit the vehicle to move slightly 
faster in water than can the amphibious jeep, the dif¬ 
ference is insufficient to outweigh the disadvantages 
of coping with large, portable, rigid pontons. 1 

Collapsible Pontons for the Jeep 

At the request of the U. S. Army Ordnance Depart¬ 
ment, attention was directed toward the design of de¬ 
tachable, collapsible pontons which could be used for 
traversing deep water. Figure 8 illustrates a method 
recommended for the jeep. Special waterproofing 
treatment would have to be given to the vehicle. No 
pilot model of this device was constructed. 4 


914 Conclusions 

With the development of waterproofing methods 
for standard Army vehicles, the value of the collaps¬ 
ible ponton in ferrying operations is potentially 
increased. Even though no satisfactory inflatable 
ponton was developed in this study, there does not 
appear to be any insurmountable design problem. 
It is therefore proposed that the investigation be con¬ 
tinued on the development of pontons which can be 
stowed and carried by the vehicles and which can 
be attached and inflated whenever desired. The ve¬ 
hicle should be able to use its own power to enter, 
leave, and travel in the water. 

92 TRAILER HITCH 

A special hitch developed for amphibious trailers 
has been constructed and shown in tests to reduce by 




Figure 8. Diagram of collapsible ponton design for stand¬ 
ard 14 -ton, 4x4 jeep. 

50 per cent the time required to connect the trailer 
to the tractor. 

In January 1945, at the request of the U. S. Marine 
Corps, work began on the development of an am¬ 
phibious trailer hitch which would simplify connect¬ 
ing the trailer to the tractor, such as an LVT or a 
DUKW, and improve the method of release.® 

In February, the first model of the hitch was de¬ 
signed. It was so constructed that upon release the 
entire mechanism is separated from the tractor and 
retained by the trailer. Field trials showed that its 
use reduces by 50 per cent the time required for mak¬ 
ing the connection. Structural failures, however, 
developed during these trials under loads closely 
approaching the maximum likely to be applied. The 
design was consequently revised and the strength 
increased approximately three times. It is believed 


li Constructed by James Cunningham, Son & Company, Roch¬ 
ester, N. Y. 

































































TRAILER HITCH 


169 



PLAN 


Figure 9. Plans for amphibious trailer hitch. 

















































































































































































































































170 


AMPHIBIOUS DEVICES 


that this modified structure (Figure 9) will operate 
satisfactorily. 7 

Although the use of this hitch with a trailer results 
in a loss of water speed—about 2 \/ knots—this does 
not seriously affect its use in specific applications by 
the Marine Corps. 

In cases where merchant vessels must literally jetti¬ 
son their cargo off the beach in order to avoid sudden 
attack, these cargoes can be picked up later in am¬ 
phibious trailers without any great urgency. 

93 SELF-PROPELLED AMPHIBIOUS 
DEMOLITION CHARGES® 

A special type of bow attachment was designed to 
give high stability to a high-speed, rocket-propelled 
amphibious demolition charge. Only limited tests 
were conducted before the end of the war, and the 
attachment was not approved for production until 
after the war had ended. 


As part of a larger program being conducted by 
Division 17 of NDRC, f a study was begun in March 
1945 on the design of a special type of bow attach¬ 
ment to give high directional stability to a high-speed 
amphibious device. This attachment (Figure 10) was 
intended to simulate the shape of a typical V-bottom 
motorboat and to keep the amphibious device from 

e Project “Snake.” 

f Summary Technical Report, Division 17, Volume 1. 




Figure 10. Plan for bow attachment for project Snake. 


heeling over and then veering in the direction of heel. 
The plan calls for bottom sections which can be de¬ 
veloped and laid in with steel. 8 

Three of these bows were later built and attached 
to the high-speed, rocket-propelled amphibious de¬ 
molition charge known as the Snake (Figure 11), and 
submitted for tests during the week of August 8, 1945 
at the U. S. Naval Amphibious Training Base at Fort 
Pierce, Florida. In the first two tests with the device 



Figure 11. Special bow attached to Snake. 



f igure 12. Snake with special bow attachment ready for 
launching from LCM(3). 


















































DEMOLITION CHARGES 


171 


launched from an LCM(3) (Figure 12), the rockets 
were faulty and failed to move the Snakes. In the 
third test, the Snake was launched about 1,800 feet 
offshore, traveled in a straight line across the water, 
beached, plowed into a wall of Japanese sen Hies three 
deep, demolished the first, overturned the other two, 
and continued on for half its own length (Figure 13). 

In another test, a Snake equipped with this bow 
landed 4 feet from the target, while units based on a 


U. S. Marine Corps design landed an average of 150 
feet from the target. 

Despite the success of these early tests, the bow de¬ 
sign was not accepted for production and instead the 
Marine Corps model was adopted. The first units 
were scheduled to be shipped to the Pacific Theater 
at the end of August. Later, however, plans were 
changed and the boat-type bow was incorporated in 
the final design, but by that time the war had ended. 



Figure 13. Snake with special bow attachment on beach 
at Fort Pierce, Florida, after offshore launching. 









Chapter 10 

AMPHIBIOUS STUDIES 


10 1 TRACK PROPULSION IN THE 
LVT CARGO CARRIER* 1 

Summary 

E xperimental towing tank tests were conducted 
on two models of the LVT cargo carrier, one with 
tracks completely submerged and the other with the 
return tracks out of the water. These studies, includ¬ 
ing measurements of resistance, self-propelled speed, 
self-propelled drawbar pull, and friction, showed that 
under the conditions of the investigation and with 
the track used the emerged track is superior. 

101,1 The Problem 

In November and December 1944, tests were con¬ 
ducted at the request of the Development Branch of 
the Office of Chief of Ordnance, Detroit, to determine 
the relative merits of emerged and submerged tracks 
for water propulsion of the LVT cargo carrier (Figure 
l). b 

10,1,2 Procedure 

Two scale models 0 were supplied for these tests, 
LVT Model N-3 (Figure 2), which operates with the 
return tracks emerged from the water and closely 

a Project OD-95. 

b This investigation was conducted at the Stevens Institute of 
Technology, Hoboken, N. J., under the supervision of Spark¬ 
man & Stephens, Inc., New York, N.Y., under OSRD contract 
OEMsr-154. 

c Supplied by the Food Machinery Corporation, Calif. 


fev • ■ - \ • 

W -.t-'-l "mmmm* mm mm - 



Figure 1. Stern view of LVT showing “controlled flow" 
track design. 


duplicates the standard LVT (2) cargo carrier in pro¬ 
duction for the Navy, and LVT Model N-4 (Figure 
3), which operates with the return tracks submerged. 
The two models have essentially the same hulls, with 
the same dimensions, tracks, suspension components, 
and drive. Model N-4 is equipped with track shroud¬ 
ing consisting of stern block, bowblock, and track 
skirt. 

Several self-propelled speed runs corresponding to 
the available range of track speeds were made with 
each model, which was guided on a straight course 
by means of the towing tank carriage, a guide chan¬ 
nel, and accelerator posts (Figures 4 and 5). Data for 
determining propulsive efficiency for each type of 
track were recorded. Stationary tests were run on both 



Figure 2. N-3 scale model of LVT for towing tank tests. 



Figure 3. N-4 scale model of LVT for towing tank tests. 



172 



















SUBMERGED TRACK PROPULSION 


173 



Figure 4. N-3 scale model of LVT showing upper track 
emerged and distinctive wave pattern. 


models and the drawbar pull was measured at various 
points in the available track speed range. 

Each model was towed at speeds ranging from 2.5 
to 5 feet per second (equivalent to 4 to 8 mph in a 
full-size prototype) with track and drive stationary, 
and records were made of resistance. 

101 - 3 Results 

These tests showed that the resistance of the N-4 
is about 5.5 per cent higher, and the self-propelled 
speed at any comparable horsepower and the draw¬ 
bar pull are both less. 

A comparison of the self-propelled speed of each 
model showed the N-3 gives a higher speed for the 
same net track horsepower, or requires lower horse¬ 
power for the same speed. This difference is appreci¬ 
able; at a speed of 4 feet per second it amounts to 
0.27 horsepower, or about 45 per cent less than the 
horsepower required by the N-4 to give the same 
speed. Correcting for difference in the resistance of 
the two models, however, indicates that about the 
same track speed is required to give the same thrust 
in each case. 

At the time of these tests, the track design as shown 
in Figure 1 was found to be the most efficient of all 
tested under the auspices of the National Defense Re¬ 
search Committee [NDRC]. 

Under the conditions of these tests and for the par¬ 
ticular track design used, the emerged track in Model 
N-3 is superior to the completely submerged track in 
Model N-4 for propulsion in water. These conclu¬ 
sions apply only to the track design tested, and the 
results do not necessarily apply to tracks that differ 
appreciably from this design. 2 



Figure 5. N-4 scale model of LVT showing completely 
submerged track. 


102 SUBMERGED TRACK PROPULSION 
Summary 

From a laboratory study of models and from field 
tests of various track-laying amphibians, it is ap¬ 
parent that in no case does the efficiency of track 
propulsion approach that which can be expected 
from screw propellers. 

For optimum performance, if both the top and 
bottom tracks of the amphibian must be submerged 
during operations in water, the track should be 
shrouded with a full bow scoop, a medium skirt, 
and a stern scoop. The track should have grousers 
formed for effective movement of the water in the 
direction of track motion. The smallest clearance 
practicable should be provided between the upper 
tips of the return track and the underside of the 
sponson. Dimensions, suspension, track, power train, 
and all items except hull and weight distribution 
should be determined on the basis of land perform¬ 
ance requirements. 

The upper track should never operate at a distance 
less than 1 foot above or below the water surface. 

In analysing submerged track propulsion, it should 
be noted that the action is not basically comparable 
to paddle wheel propulsion. 

10 21 The Problem 

Because of military requirements, many track-lay¬ 
ing vehicles have been converted by one means or 
another into amphibians. In many cases, this con¬ 
version has resulted in totally submerging the tracks, 
which must be used for propulsion in water. In order 
to improve the performance of existing and proposed 





















174 


AMPHIBIOUS STUDIES 


vehicles of this type, an investigation was requested 
in the summer of 1943 by the Development Branch of 
the Office of Chief of Ordnance, Detroit, on amphib¬ 
ious cargo carriers, gun carriages, tank conversion 
equipment, and self-propelled track-laying models.' 1 

102,2 Procedure 

Full-scale propulsion tests were conducted on the 
Weasel M-29C amphibious light cargo carrier, e the 
standard T-70 gun motor carriage equipped with 
simple track shrouding (Figure 6), the T-6 conversion 
equipment for the M-4 medium tank 1 ’ and the T-7 
conversion equipment for the M-18 gun motor car¬ 
riage. 8 Drawbar and speed tests were conducted on 
these units as modified with different types of tracks, 
grousers, and shrouding. 

For the self-propelled model studies, extended 
studies were conducted on a unit as shown in Figure 
7, with an over-all length of 45]/ 2 inches, a width of 
14i/£ inches, a weight of 104 pounds, suspension simi¬ 
lar to that on the T-70, and a track driven by an 
electric motor mounted inside the hull. 11 

Measurements were made of the resistance of the 
model first with the tracks stationary and then with 
the tracks moving, of the speed of the model at differ¬ 
ent track speeds, and of the friction of the test setup. 
These were compared with drawbar ptdl tests made 
with the model stationary and connected to a cly- 

fi This investigation was conducted by Sparkman & Stephens, 
Inc., New York, N.Y., under OSRD contract OEMsr-154. 

p See Chapter 5 in this volume. 

f See Chapter 9 in this volume. 

s See Chapter 6 in this volume. 

h These studies were conducted at the Webb Institute of 
Naval Architecture, New York, N. Y., and the Stevens Experi¬ 
mental Towing Tank, Hoboken, N. J. 



Figure 6. Experimental installation of simple track 
shrouding for submerged track propulsion study on T-70 
gun motor carriage. 



Figure 7. “Model 500,” self-propelled model used in sub¬ 
merged track propulsion studies and shown equipped 
with bowblocks and medium skirt. 


namometer. To permit an evaluation of the factors 
underlying the results, these measurements were made 
with various modifications of (1) clearance between 
the underside of the sponson and the top of the re¬ 
turn track, (2) bowblocks, (3) skirts and skirt holes, 
(4) stern arrangements, (5) operating water line, and 
(6) tracks (see Figure 8). 

102,3 Results 

From the detailed data, 1 it is possible to summarize 
the findings on both full-scale and small-scale models 
as follows: 

Clearance 

Proper clearance between the top of the track and 
the underside of the sponson can materially improve 
speed. With more efficient grouser-type tracks, mini¬ 
mum possible clearance may be most readily achieved. 
With less efficient tracks of the steel or rubber block 
type, increased clearance up to about 6 inches (the 
highest equivalent clearance tested) results in in¬ 
creased speed. 

Bowblocks 

The bowblock is the most important single item 
of shrouding, and should be provided in every case 
in as complete a form as possible. When possible, a 
bowblock design with full scoop should be used, and 
all efforts made to discharge the water from the re¬ 
turn track tunnel through the largest angle down 
and back into the track. Discharge down and back is 













SUBMERGED TRACK PROPULSION 


175 



Figure 8. Details of track and shrouding components. 

















































































































176 


AMPHIBIOUS STUDIES 


desirable even at the sacrifice of angle of turning, up 
to at least 60 degrees in some cases. In any given bow- 
block, the efficiency is increased by increasing the 
angle of turn from dead ahead to 180 degrees. 

In all bowblock design, emphasis must be placed 
on providing free, unrestricted flow of water in and 
out at all times. Restrictions and conflicting flow 
patterns are definitely harmful. 

Vulnerability and other considerations for land 
performance may occasionally limit the completeness 
of the bowblock to the extent that a removable or 
sliding block may be necessary for optimum amphibi¬ 
ous operation. In cases where this is not practicable, 
the use of a stern wing as an alternate is suggested. 

Track Skirts 

From tests on both small- and full-scale models, it 
was found that track skirts extending to the hull bot¬ 
tom must be used to increase thrust and reduce resist¬ 
ance. To permit track servicing and track clearing 
in mud, they should be hinged at the sponson line. 
Since the skirts are exposed and subject to damage, 
special care should be given to support them at both 
top and bottom, and to permit quick removal. 

Shaping the skirt to conform more closely to sus¬ 
pension outline is not expected to yield any marked 
improvement. 

Track Skirt Holes 

The tests show that these holes help slightly with 
block tracks and hinder with grouser-type tracks. 
Experimentation with track skirt holes may there¬ 
fore prove fruitful where the track has relatively 
small grouser area and limited clearance. In this 
case, holes in the after end of the skirt and above the 
return track are those most likely to improve per¬ 
formance, but the anticipated improvement is slight. 

Stern Arrangements 

Careful design and application of the stern scoop 
should yield marked improvement in water speed. 
For highest speed, the scoop should extend down to 
at least the center line of the rear idler. 

Stripping at any point in the track travel path is 
harmful. 

The stern wing should be considered only when a 
substitute for a bow scoop is necessary. For both 
land and water operation, the wing has practical 
disadvantages which should be included in any con¬ 


siderations for application. Careful investigation of 
clearance over the track forward of the wing is rec¬ 
ommended for improving track performance. 

Tracks 

In general, track design must be guided by relative 
importance of land performance and water perform¬ 
ance and similar over-all considerations. 

Where performance in water is paramount, the 
best track is the double chevron type, with the 
grousers about 3 inches high. 1 rack efficiency in¬ 
creases with track and grouser width throughout the 
range tested, and accordingly the track should be as 
wide as possible. 

Where performance on land and performance in 
water are about equally important, the standard 
rubber or steel block track with the steel or rubber 
chevron grouser and wing end connector extensions 
are recommended. These and all grouser tracks 
should be run with the open end leading. 

Where land performance is the primary considera¬ 
tion, the track selected for optimum land operation 
will give reasonably satisfactory water performance 
if the recommended shrouding is used. 

The primary consideration in designing a track 
for water propulsion is the direction of a high per¬ 
centage of the total water moved by the track in the 
direction of track motion. Thus, grousers or webs 
which have a minimum of edge leakage have cor¬ 
respondingly high efficiency. 

Lightening or mud clearing holes through the 
track block should be used where these will improve 
performance other than water propulsion. 

Track Depth 

Efficient design should guarantee complete sub¬ 
mergence of the entire track under all conditions of 
water operation. The water line should be well above 
the sponson lines and far from the return track levels. 
This is significant not only for amphibians with all 
tracks submerged, but also for those with the return 
tracks emerged, and these should have the return 
track no less than 1 foot above the water line. 

The submerged return track design is generally 
favored by considerations of land performance. It 
makes possible shorter tracks, better suspension sys¬ 
tems, and greater stability on land and in water as 
a result of better weight distribution. Experience 
has shown that, in the case of combat amphibians, 
the submerged return track design minimizes chances 





ASSAULT ACROSS MUI) 


177 



Figure 9. Effect of shrouding and track design on track 
propulsion. Standard is mean skirt, standard bowblock, 
block track. Improved is mean skirt, full bow scoop, best 
stern scoop, 1,4-inch double chevron grouser, 2-inch pitch 
on block track. 

of enemy detection by means of phosphorescent track 
spray. 

10 - 2 - 4 Conclusions 

In general it was found that in no case does effi¬ 
ciency of track propulsion approach that which can 
be expected from screw propellers. 

Drawbar pull is a good criterion of relative pro¬ 
pulsive efficiency. 

The extent of improved performance due to better 
shrouding is independent of that due to track design, 
and the two may be combined together for maximum 
improvement (Figure 9). 

Recommended design features include a com¬ 
pletely submerged track with a full bow scoop, a 
medium skirt, and a stern scoop, and a track with 
grousers formed for efficient motion of the water in 
the direction of track motion. Minimum practicable 
clearance should be provided between the upper 
tips of the return track and the underside of the 
sponson. The dimensions, suspension, track, power 
train, and all items except hull and weight distribu¬ 
tion should follow requirements for land perform¬ 
ance. 

Regardless of whether the vehicle is designed with 


emerged or submerged return track in any condition 
of trim or loading, this track should never operate at 
less than 1 foot from the water surface. 

All track-laying amphibians should be equipped 
with the best practicable shrouding, regardless of the 
means of propulsion used, to reduce resistance and 
provide normal or emergency water operation. 

In analysing submerged track propulsion it should 
be noted that the action is not basically comparable 
to paddle wheel propulsion, and that more power is 
dissipated at turns in the track than in the straight 
portions. 

103 ASSAULT ACROSS MUD 

At the request of the Amphibious Section, 
COMINCH, means were studied for assaulting 
across mud. Rocket-propelled landing craft were pro¬ 
posed, and rough performance estimates made in con¬ 
junction with Divisions 6 and 8. d 

The tactical assumption was made that a nonstop 
ship-to-shore passage across all types of mud provided 
the most powerful assault doctrine. To meet these 
requirements, it is essential to keep unit ground pres¬ 
sure low (for soft mud), and to provide high thrust 
(for dry and sandy mud). 

It was found that although rocket propulsion offers 
distinct possibilities for an assault across mud, the 
range would be extremely limited by the basic in¬ 
efficiency of rocket propulsion at the relatively low 
speeds involved. The problem of obtaining continu¬ 
ous propulsion by successive discharge of rockets was 
not studied in detail, but does not appear to offer a 
simple solution. 

Figure 10 shows the relationship between time and 
distance, the latter expressed as the ratio between 
the distance travelled and the square root of the 
length of the vehicle. Each curve represents a dif¬ 
ferent value of /, which equals the ratio of jet reac¬ 
tion to displacement. Figure 11 shows the relationship 
between time and speed, the latter expressed as the 
ratio between the velocity and the square root of the 
length of the vehicle. 5 

Designs were prepared to meet the requirements by 
mounting jet units on a V-bottom hull (Figure 12) 
and on an inverted V-bottom hull (Figure 13). The 
designs were not adopted, preference being shown for 
an air-propelled scow towing a Weasel across the soft 
mud, the troops to transfer to the Weasel if the mud 
becomes dry, sandy, or inclined. 





= DIST. / vT 


178 


AMPHIBIOUS STUDIES 



01 23456789 10 


TIME - SECONDS 

Figure 10. Relationship between time and distance trav¬ 
elled by rocket-propelled landing craft over mud. 

J = ratio of jet reaction to displacement, 

L = length of vehicle. 



Figure 11. Relationship between time and speed of travel 
by rocket-propelled landing craft over mud. 

J = ratio of jet reaction to displacement, 

L = length of vehicle. 





Figure 12. V-bottom, jet-propelled assault landing boat. 






















































FUNDAMENTALS OF DESIGN 


179 





PROFILE AT A-A 


Figure 13. Inverted V-bottom, jet-propelled assault landing boat. 


10.4 fundamentals of amphibious 
VEHICLE DESIGN 

Summary 

A survey of the development of amphibians makes 
possible an evaluation of the relative merits of 
ground-up designs and conversion designs, and a con¬ 
sideration of the fundamental principles involved. 

10 - 41 Introduction 

With the completion of amphibious design studies 
under the direction of Division 12 of NDRC, a sur¬ 
vey' 1 * of the significant problems involved has indi¬ 
cated various principles and procedures which may 
be useful in future investigations. 4 


In this report, some of the conclusions are derived 
from experimental and field data. Others are opin¬ 
ions based on preliminary observations or considera¬ 
tions. 1 

10 4 2 Design Procedures 

The development of all amphibious vehicles can 
be divided roughly into two broad categories— 
ground-up designs and conversion designs. 

Ground-up Designs 

Designing from the ground up, which yields a com¬ 
pletely new vehicle, is the method followed almost 


i For supporting data and other information, see the bibliog¬ 

raphies for Chapters 2 to 9. 






























































180 


AMPHIBIOUS STUDIES 



Figure 14. Jagger 1926 amphibian using Ford Model T 
components with chain drive to rear wheels and remov¬ 
able paddle wheels for water propulsion. Water speed 
about 4 mph. 



Figure 15. Jagger 1928 “Honukai” using Ford Model A 
components with twin propellers mounted above rear 
axle, one on each side of differential. Water speed about 
5 mph. Springing of rear axle was eliminated after early 
trials. 


exclusively before 1941 and used by some designers 
after that date. It offers complete freedom to the de¬ 
signer, permitting the use of new or standard com¬ 
ponents in any proportion or any arrangement. 

Typical of the wheeled vehicles designed in this 
manner are the following: 

1. The 1926 Jagger amphibian using Ford Model 
T components, with chain drive to the rear wheels 
and removable paddle wheels for water propulsion 
(Figure 14). 

2. The 1928 Jagger Honukai using Ford Model A 
components, with twin propellers mounted above the 
rear axle, one on each side of the differential (Figure 
15). 

3. A German wheeled amphibious scout car dem¬ 
onstrated in 1937 (Figure 16). 

4. A German scout car, captured in France in 1944, 
which has a mechanical power take-off from the 



Figure 16. German amphibious wheeled scout car dem¬ 
onstrated in 1937. 


vehicle engine and a retractable outboard drive with 
a single screw propeller off the stern (Figure 17). 

5. The 4x4, 3/£-ton Aquacheetah first demonstrated 
in May 1941 and improved in 1942 (Figure 18). 

6 . The British 8x8, 5-ton Terrapin Mark 1 and 
Mark 2 amphibious cargo carriers powered by two 
Ford V-8 engines and designed to be manufactured 
quickly even though certain disadvantages, including 
lack of maneuverability on land, were apparent. 

Among the track-laying amphibians designed in 
this way are the Roebling Alligator, later modified 
and used by the U. S. Army (Figure 19), an experi¬ 
mental amphibious light tank equipped with a screw 
propeller and demonstrated by the Japanese in 1939 
(Figure 20), and a Japanese twin screw-propelled 



Figure 17. German amphibious wheeled scout car, cap¬ 
tured in France in 1944. propelled by retractable out¬ 
board drive. Marine power provided by mechanical 
power take-off from vehicle engine. 













FUNDAMENTALS OF DESIGN 


181 




Figure 20. Experimental screw-propelled amphibious 
light tank demonstrated by Japanese about 1939. 


Figure 21. Japanese “ground-up” light tank design for 
intermittent amphibious operation. Bow and stern pon¬ 
tons are closely integrated with main hull but are readily 
jettisoned for land operation. Twin screw propelled. 
Model shown captured summer 1944. 


Figure 18. 1942 model of “Aquacheetah” representing 
“ground-up” design of J^-ton, 4x4 amphibian built by 
Amphibian Car Corp. 

light tank, captured in 1944, designed for intermit¬ 
tent amphibious operation with bow and stern pon¬ 
tons which are closely integrated with the main hull 
but which can be readily jettisoned for land opera¬ 
tion (Figure 21). The outstanding development in 
this class is the LVT [Landing Vehicle, Tracked], 
which was extensively used in various forms by the 
Armed Forces of the United States and Great Britain 
(Figure 22). 

Despite the usefulness of ground-up designing, 
experience has shown that this method has its in¬ 
herent disadvantages, notably the serious mechanical 
and production problems which almost invariably 
arise during the development of any completely new 
chassis. The development of satisfactory land per¬ 
formance becomes an unavoidably long program. 
Basic design changes often are found to be neces¬ 


Figure 19. Early model of “Alligator” track-propelled 
amphibian representing “ground-up” design by John A. 
Roebling. 


sary only after extended field trials and actual com¬ 
bat operation. 

The grouncl-up method is recommended if funds, 
development facilities, and especially time are all 
abundantly available. If any of these factors is lim¬ 
ited, as in time of war, careful evaluation of the over¬ 
all program is essential. 


Conversion Designs 


In contrast to the ground-up method is the con¬ 
version design, which converts a standard land ve¬ 
hicle or its chassis into an amphibious vehicle—a pro¬ 
cedure which, to a very large extent, was originated 
by Division 12 of NDRC and its contractors. Here 
the designer has the advantages—as well as the limita¬ 
tions—of starting with a basic structure selected for 
its land performance, its known reliability, and its 
availability for production. 

In a few instances, the conversion may be for only 










182 


AMPHIBIOUS STUDIES 



Figure 22. Unarmored LVT(2) track-propelled cargo 
amphibian. 


temporary amphibious operation, and the land ve¬ 
hicle is equipped with detachable lloats or pontons 
which provide the necessary added buoyancy, reduce 
water resistance, and sometimes act as shrouding to 
improve propulsion by tracks. This method is illus¬ 
trated by an early use of side pontons on the 4x4, 
^-ton truck (Figure 23), and by the Ritchie 4-6 
device, which consists of metal pontons attached to 
the M-4 medium tank to give satisfactory speed and 
general performance in water (Figure 24). The pon¬ 
tons may be readily jettisoned for land operation of 
the tank. 

For permanent amphibious operation, a water¬ 
tight hull is fitted around a standard land vehicle 
chassis so that it will perform satisfactorily both on 
land and in water. 

Permanent amphibious wheeled vehicles include 
the DUKW 6x6, 2i/4-ton cargo carrier (Figure 25) and 
the GPA 4x4, 14 -ton cargo carrier (Figure 26). Here 
the land body is replaced with a new amphibious 
hull. The wheels, suspension, drive shafts, differen¬ 
tial, and pertinent supports, all taken from the stand¬ 
ard chassis, become wet appendages housed to 



Figure 23. Early “temporary conversion” of 14 -ton, 4x4 
truck demonstrated in 1941. 


varying degrees in tunnels (Figure 27), while the 
frame, engine, power train controls, and auxiliary 
equipment are housed within the watertight hull. 
Provisions are also made for sealing against water 
entrance, providing engine-cooling air through pro¬ 
tected inlets and outlets, screw propeller drive for 
water operation, rudder steering, and numerous ac¬ 
cessories and refinements for both land and water 
operation. Safety devices, including folding surf 
plates, power-driven bilge pumps, and coamings 
must likewise be included. 

One type of permanent conversion for track-laying 
vehicles is shown by the conversion of the M-29 
Weasel light cargo carrier to the M-29C Weasel am¬ 
phibious light cargo carrier (Figure 28). This was 
accomplished by the addition of watertight bow and 
stern cells, track shrouding, rudder steering equip¬ 
ment, and such auxiliaries as a surf plate and a 
power-driven capstan. Water propulsion is obtained 
from the standard M-29 land track with shrouding 



Figure 24. M-4 A1 medium tank equipped with Ritchie T -6 flotation device. 







FUNDAMENTALS OF DESIGN 


183 



Figure 25. Late 1944 production model of 2i/2' ton ’ 6x6 

DUKW. 

developed to increase the effective thrust of the mov¬ 
ing track. 

Another type is illustrated by the conversion of the 
M-18 76-mm gun motor carriage to the T-86 amphibi¬ 
ous gun motor carriage (Figure 29). in this case the 
standard hull from the sponson up was removed and 
replaced with a new, larger, watertight hull with a 
raised turret and ends designed for increased buoy¬ 
ancy and decreased resistance. 

In general, this method of design was adopted in 
1941 in order to expedite the development and pro¬ 
duction of urgently needed vehicles. It provided the 
designers with engineering and held experience based 
on standard, proved chassis, enabling them to devote 
most of their efforts to marine performance and re¬ 
quiring only refinements of land performance. Exist¬ 
ing production equipment and assembly methods 
could be adopted, often without change, and main¬ 
tenance in war theaters could be based on available 
methods and spare part supplies set up for the parent 
vehicles. 

Inevitable disadvantages were inherent in this 
method, since the parent vehicles had been designed 
with little or no thought given to operation in water. 
Only rarely did the original weight, arrangement, 
and materials meet amphibious requirements. On 
the other hand, these disadvantages were offset to 
some degree by the large number and variety of land 
vehicles available for selection as the parent vehicle, 
the contemporary development of improved com¬ 
ponents, and the ability to incorporate into produc¬ 
tion models certain modifications found desirable or 
necessary for amphibious operation. 

Because time was so important, it is believed that 
the conversion design method has amply justified 
its use. Its introduction and adoption in 1941 as a 
major design procedure resulted in developing and 
delivering useful vehicles to the Armed Forces more 



Figure 26. Production model of amphibious jeep. 


quickly than would have been possible by any other 
means. 

10 4 3 Basic Specifications 

In outlining principles and correlating informa¬ 
tion, the bulk of the material presented here repre¬ 
sents data obtained from amphibians which are 
permanent conversions of standard land vehicles 
or their chassis. While this applies in particular to 
conversion designs, the principles apply generally to 
all amphibians, with only slight reservations in some 
cases. Vehicles for only military use are considered 
here. 

In the design of a new amphibious vehicle, certain 
basic limitations are involved. Some of these are defi- 



Figure 27. Rear view of early pilot model of amphibious 
jeep representing “conversion” design. 
























184 


AMPHIBIOUS STUDIES 


nite, while others require a compromise based on the 
judgment of the designer. Over-all width and weight, 
for example, are definite specifications, with width 
usually limited by considerations of rail transport or 
the width of military roads and bridges; gross and 
light weight may be rigidly determined by the pro¬ 
posed use of the vehicle and by the size of the avail¬ 
able engine in combination with the size of the hull. 

Less definite but nonetheless limiting specifications 
include over-all height, which must be a minimum 
for land operation to reduce exposure to enemy fire 
and a maximum to provide adequate freeboard in 
water and adequate driver vision on land. Over-all 
length must be determined by such factors as ma¬ 
neuverability on land, suitable angles of approach 
and departure, driver vision, and adequate protec¬ 
tion of cab and openings from surf and rough water. 

Because in many cases the final design details rep¬ 
resent a compromise between the conflicting require¬ 
ments for land operation and w'ater operation, in 
most respects the amphibian becomes inferior in 
w T ater performance to a comparable boat and inferior 
in land performance to a vehicle designed solely for 
land transport. It is inferior to a boat in having high 
resistance, due largely to numerous appendages and 
to greater weight for the same job. It is inferior to a 
land vehicle in having greater bulk, because of the 
necessity for providing buoyancy, and an excess of 
mechanical parts, essential for propulsion in the 
w'ater. 

On the other hand, the amphibian possesses certain 
marine advantages over its boat counterpart, as well 



Figure 28. Side view of early model of M-29C amphibious 
Weasel representing “conversion” design. This represents 
conversion of nonamphibious M-29 Weasel by addition 
of bow and stern cells, track shrouding, and rudder 
steering. 

as land performance advantages over its parent land 
vehicle. 

Figure 30 and Table 1 together serve to compare 
a typical amphibian, the DUKW, with its parent 
truck and with two corresponding boats. The char¬ 
acteristics they evaluate are true to different extents 
for all amphibians. Future development should aim 
at reducing these differences. 

Hull Type 

It will be shown later that the length, width, 
height, angles of approach and departure, and ground 
clearance define the block or envelope within which 
the amphibious hull must fall. The designer may 
exceed these limitations only when this is warranted 
by an inescapable compromise; otherwise, the limit¬ 
ing dimensions can be outlined immediately for the 




















FUNDAMENTALS OF DESIGN 


185 






Figure 30. Comparison of DUKW amphibian and parent CCKW truck with Boat A (comparable hull dimensions) 
and Boat B (comparable boat displacement). 


wheeled, track-laying, half-track, or tractor-trailer 
amphibian. 

The best of all hull types tested for the DUKW is 
a scow type with full ends and with wet appendages 
housed in tunnels (Figure 31). This design provides 
for maximum buoyancy with limited over-all dimen¬ 


sions. Full ends are useful in entering or leaving the 
water over a steep bank, and their buoyancy helps to 
prevent swamping. Tests proved conclusively that, 
for appendages such as wheel and differential casings, 
the greater the housing in a tunnel, the less the re¬ 
sistance in the water. Tunnels, moreover, protect ap- 
















































































































































































186 


AMPHIBIOUS STUDIES 


Table 1. Comparison of a Successful Amphibian (DUKW) with Two Corresponding Boats 

and Its Parent Land Truck. 


I terns 

Amphibian 


Truck 

Boat A 

Boat B 

General description 

DUKW—2i/2 t.—6x6 wheeled am¬ 
phibious cargo carrier with winch 

CCKW -214 t.- 
6x6 cargo long 
wheelbase—with 
winch 

General purpose 
boat with same 
WL length and 
beam as DUKW 

General purpose 
boat with same 
displacement as 
DUKW 

Hull type 

Scow type—wheels, housed wheels, 
axles, drive shafts, differentials, 
brakes—wet—in tunnels 


Round bottom 
non-planing 

Round bottom 
non-planing 

Length over-all (inches) 

372 


267 

369 

483 

Breadth over-all (inches) 

96 


88 

124 

160 

Height over-all 
in water (from WL) (inches) 

59 



72 

74 

on land (over cab) (inches) 

103 


87 

.... 


Length load water line (LWL) (inches) 

314 



314 

456 

Maximum beam at water line (inches) 

94 


.... 

94 

124 

Maximum hull draft—loaded in sea 
water (inches) 

30 



18 

24 

Loaded freeboard to deck in sea water (64 lb/cu ft) 

over bow (inches) 23 



65 

66 

amidships (inches) 

19 



52 

54 

over stern (inches) 

15 



53 

55 

Displacement or weight- 
loaded (pounds) 

20,000 


15,900 

8,100 

20,000 

light (pounds) 

15,000 


10,900 

5,400 

9,500 

Normal payload (pounds) 

5,000 


5,000 

2,700 

10,500 

Pounds payload per pound of weight 
light 

0.33 


0.46 

0.50 

1.10 

Cargo floor area (square feet) 

85 


80 

120 

210 

Cargo volume—top of coaming (cubic feet) 

198 


280 

540 

1 ,050 

Ground clearance (min. at front axle) 
(inches) 

iiy 4 


10 



Ground clearance btwn front and rear 
wheels (inches) 

is y 2 


17 



Angle of approach (degrees) 

38 


31 



Angle of departure (degrees) 

25 


36 



Beam-draft ratio (fully loaded) 

3.14 



5.21 

5.16 


Based on hull 
Based on actual with no cutouts 
displacement to or appendages 
load water line to same WL 




Displacement-length ratio 

displacement long, tons 
(LWL/100) 3 ft 3 

378 

569 


153 

163 

, „ . volume displacement 






LWL x Max. beam x draft 

0.557 

0.823 


0.371 

0.398 

Longitudinal prismatic coef. 

volume displacement 






max. section area x LWL 

0.671 

0.835 


0.566 

0.566 














FUNDAMENTALS OF DESIGN 


187 



Table 1. ( Continued) 




Items 

Amphibian 

Truck 

Boat A 

Boat B 

Range of operating speed-length ratio 





,— speed knots 

17 VZ —j - — 7 = 

Vlwl VfF 

0.7-1.0 


0.9-1.3 

0.9-1.3 

Speed at F/Vl = 1.0 mph 

Total resistance in pounds per long, ton 

6.16 


6.16 

7.09 

displacement at F/VZ = 1.0 

Total resistance (fully loaded) at 

124 


21 

24 

F/VZ = 1.0 lb 

1,100 


76 

215 

Wetted surface (square feet) 

740 


210 

370 

% residual resistance of total resistance 
Transverse nretacentric height (GM T ) 

85 


32 

28 

(inches) 

25 


47 

82 

Longitudinal metacentric height (GMJ 





(feet) 

48 


58 

75 

Moment to trim 1" on load WL 





(foot-pounds) 

2,790 


1,370 

3,290 

Pounds per inch immersion load WL 

1,190 


870 

1,532 

Typical propellers 

1-3 blade—25" diam. x 14" pitch 


1-3 blade — 

1-3 blade — 


at 1,100 rpm 


18" diam. x 16" 

20 " diam. x 16" 




pitch at 500 rpm 

pitch at 625 rpm 

Wake fraction 

0.25 


0.08 

0.08 

Thrust deduction 

0.30 


0.10 

0.10 

, . . tow rope hp (per cent) 

Propulsive coef. =-*-— - - 

engine brake hp 

20 


55 

55 

Apparent propeller slip (per cent) 

Miles per gallon gasoline over operating 

58 


15 

22 

speed range in water 

0.8 @ 6 mph—2.3 @ 4.2 mph 


13.0 @ 6.4 mph 

7.4 @ 7.4 mph 


pendages from damage in shallow water and on land. 
Impact and concentrated loads resulting from cross¬ 
country operation require that the hull be strength¬ 
ened well beyond marine requirements and demand 
that metal be used for the hull shell. 

In comparison, for Boats A and B (Figure 30 and 
Table 1), greater latitude of hull form is permissible 
because no land performance is involved, and the 
hulls can be designed simply for space, speed, or con¬ 
siderations of cost. A round bottom is selected as 
being typical for comparable speed ranges. The ma¬ 
terial used in construction need not be metal, and 
protection from local impact is not as vital as in the 
case of the amphibian. 

Similarly, greater leeway is permissible in the de¬ 
sign of the land truck body, and the construction may 
vary according to the purpose of the vehicle, the gen¬ 
eral type of its cargo, and the methods to be employed 
in loading and unloading it. 


Length 

The DUKYV is snbstantially shorter than a com¬ 
parable boat with the same displacement. This is 
necessary to maintain satisfactory maneuverability 
on land, but unfortunately it increases resistance in 
the water and adds to the draft or the beam (up to 
the over-all width limitation) or both. 

In the same way, the length of a full track-laying 
amphibian is still further limited for satisfactory 
land maneuverability, particularly for adequate 
angles of approach and departure. For an allowable 
center-of-track to center-of-track dimension, the 
length of track on the ground is clearly limited by 
the degree of maneuverability desired. 

A half-track or ^-track vehicle such as the pro¬ 
posed model shown in Figure 32 offers the most satis¬ 
factory method of increasing the over-all length, 
while a tractor-trailer such as the proposed unit 
shown in Figure 33 offers potentially greater length 


















188 


AMPHIBIOUS STUDIES 



BOTTOM VIEW 






Figure 31. Hull of 2i/ 2 -ton, 6x6 DUKW amphibian showing tunnels and cutouts. 


with satisfactory maneuverability on land. For am¬ 
phibians of high gross weight—35,000 pounds or 
more—either of these types is recommended in place 
of the full-track or wheeled amphibian, and would 
offer better arrangement, greater cargo space, and 
better water performance. 

Length, therefore, is determined essentially by land 
requirements. The length of an amphibian can be 
that of a comparable land vehicle plus end exten¬ 
sions, with consideration for satisfactory angles of 
approach and departure. 

Width 

The width of the DUKW is also limited by land 
specifications. Rail transport limits such a vehicle 
to 124 inches, while military bridges and roads may 
reduce the maximum width to 96 inches. In contrast, 
a similar boat may have a beam far surpassing such 
limits. 


Height 

The over-all height of an amphibian must be de¬ 
termined by an arbitrary decision based on judgment 
and experience, and on such factors as maintaining 
a low profile to reduce exposure to enemy artillery 
fire, keeping the deck height down in order to facili¬ 
tate loading and unloading, maintaining sufficient 
freeboard and reserve buoyancy for rough water op¬ 
eration, and providing a satisfactory vantage point 
for driver vision in land operation. 

These limitations do not affect such water craft as 
Boats A and B, or are not critical. 

Loaded Freeboard 

File DUKW freeboard of 23 inches to the deck at 
the bow and 15 inches at the stern is apparently just 
enough for all-around seaway and surf operation, 
provided that all cooling-air inlets and outlets, cargo 
spaces, and other large openings are protected or 
























































































































FUNDAMENTALS OF DESIGN 


189 



Figure 32. Side view of model of proposed 15-ton, s^-track amphibious cargo carrier. 


covered. The freeboard required and obtainable will 
differ for each amphibian. 

Figure 30 and 'Fable 1 illustrate how readily free¬ 
board can be increased on boats. Moreover, a sea¬ 
water cooled engine requires no protection for 
cooling-air inlets and outlets. Such a cooling system 
could be installed on an amphibian, but different 
cooling systems would then be required for land and 
water operation. 

Payload and Payload Ratio 

The ratio of payload to weight light is somewhat 
lower for the amphibian than for the parent land 
truck, and appreciably lower than for either of the 
comparable boats. This is due to the increased hull 
bulk in the amphibian, the added propulsion equip¬ 
ment, and the provision of such safety equipment as 
a surf plate and a bilge pump. Other factors inherent 
in the conversion-design method tend to decrease the 
payload ratio of the amphibian. This higher weight 
of the unloaded vehicle results in increased fuel con¬ 
sumption, increased maintenance, and shorter vehi¬ 
cle or component life. 

Cargo space is necessarily smallest in the amphib¬ 
ian, where it is limited by the basic dimensional fac¬ 



tors and by the need for decking at the ends. This 
decking is more necessary with the amphibian be¬ 
cause of its low freeboard in normal water operation 
and because vertical displacement of its end in rela¬ 
tion to the water line may be very great as it enters 
or leaves the water (Figure 34). 

Angles of Approach and Departure 

To enable the amphibian to climb small knolls or 
steep sand chines, its angle of approach should be 
somewhat greater than its grade ability. 

Its angle of departure should be not less than 30 
degrees, and should be sufficient to permit rear wheel 
traction when starting to climb out of a steep ditch. 

Ground Clearance 

Clearance is apparently involved only in land op¬ 
eration, but actually it affects the determination of 
over-all height for a given hull volume. Thus, an 
arbitrary decision must be made as a compromise be¬ 
tween maximum clearance and minimum vehicle 
height. 

Ratio of Beam to Draft 

Like all other amphibians, the DUKW has a ratio 
of beam to draft which is lower than that in com- 



Figure 33. Artist’s conception of proposed amphibious tractor-trailer units in operation. 




jfcvgaiaiNioi 


ffl- 










































190 


AMPHIBIOUS STUDIES 



Figure 34. Climbing steep river bank, rear deck of am¬ 
phibious jeep is partly submerged. Most entries down 
such banks similarly immerse foredeck. 

parable boats, and consequently gives lower trans¬ 
verse form stability. Compensation is provided in 
part by increased displacement of the amphibians, 
a lower center of gravity, and an appendage effect. 

Displacement-Length Ratio 

This ratio is inevitably high on amphibious vehi¬ 
cles because of unavoidably high weight and limited 
over-all length, and indicates a relatively high hull- 
form wave-making resistance. This ratio is about 
1,300 in the LVT(4), and about 569 in the DUKW. 
The possibility of substantially reducing this ratio 
is provided by the larger ^-track or tractor-trailer 
unit amphibians. 

Block and Longitudinal Prismatic Coefficients 

These values, criteria of residual hull-form resist¬ 
ance, are high in amphibians because of the dimen¬ 
sional limitations involved. 



Figure 35. Scale model of 15-ton, y<j-track amphibian be¬ 
ing tested in towing tank. Wave pattern is typical for 
amphibians operating at a speed equivalent to a speed- 
length ratio of 1.0. 


Speed-Length Ratio 

In military operations, the use of low-displacement 
boats may be predetermined by their practical operat¬ 
ing speeds. Since less additional power is needed, they 
can be more easily designed for higher speeds than 
can comparable amphibians. 

In the case of the DUKW, the operating speed- 
length ratio is relatively low, but at the sacrifice of 



V(KNOTS) 

SPEED-LENGTH RATIO = — - - «V/ 

VWL LENGTH (FT) /VL 


Figure 36. Relative water resistance of various amphib¬ 
ians and typical boat. (1) Amphibian based on 6-ton, 6x6 
Brockway, with boat hull, axles, wheels, etc., as unhoused 
appendages. Over-all length 41 feet 0 inches, gross weight 
40,000 pounds; (2) Amphibian based on 6-ton, 6x6 Brock¬ 
way with DUKW-type hull, axles, wheels, etc., housed in 
tunnels. Over-all length 41 feet 0 inches, gross weight 
40,000 pounds; (3) M-29C amphibious Weasel. Over-all 
length 14 feet 5 inches, gross weight 6,000 pounds; (4) 
2 i/2-ton, 6x6 DUKW. Over-all length 31 feet 0 inches, 
gross weight 20,000 pounds; (5) 15-ton, s / 4 -track amphib¬ 
ious cargo carrier. Over-all length 41 feet 6 inches, gross 
weight 70,000 pounds; (6) i/^-ton, 4x4 amphibious jeep. 
Over-all length 15 feet 8i/ 2 inches, gross weight 3.400 
pounds; (7) LVT(2). Over-all length 24 feet 5 inches, gross 
weight 34,900 pounds; (8) T-86 amphibious gun motor 
carriage. Over-all length 29 feet 3 inches, gross weight 
44,000 pounds; (9) Round-bottom pleasure cruiser (not 
an amphibian). Over-all length 52 feet 7 inches, gross 
weight 43.200 pounds. All track-laying amphibians tested 
with tracks stationary. 






















FUNDAMENTALS OF DESIGN 


191 




Figure 37. Scale model of amphibian based on Brockway 
6-ton, 6x6 chassis. This design emphasizes hull form, 
eliminates appendage tunnels. Resistance is higher than 
all other types of hulls tested. 

fuel consumption and cruising range this vehicle can 
give higher speeds adecpiate to fulfill its missions. 

Resistance 

Since it is determined largely by land require¬ 
ments, the hull form of an amphibian generally has 
higher form resistance than does a comparable boat. 
Figure 35 shows the wave pattern typical for am¬ 
phibians operating at a speed equivalent to a speed- 
length ratio of 1.0. Appendage resistance more than 
doubles hull resistance. 

The relative resistance of a number of wheeled, 
full-track, and 34 -track amphibians and a round-bot¬ 
tom, nonamphibious pleasure cruiser is indicated by 
the curves in Figure 36. These show that while the 
resistance per ton varies over a wide range, the lower 
limits for amphibians are well above the upper limits 
for comparable boats, due to high basic hull-form re¬ 
sistance and to extremely high residual resistance 
caused by numerous appendages. 

The curves likewise show that the total resistance 
of a given amphibian does not vary with displace¬ 
ment in any approximate ratio. This is true since 
practically all the amphibian’s appendages are im¬ 
mersed even when the vehicle is unloaded, and their 
resistance does not increase in proportion to an in¬ 
crease in vehicle draft. Thus, the low values of re¬ 
sistance per ton of displacement for the LVT, the 
^4-track, and the T-86 are due in large measure to 
the higher displacement and lower appendage resist¬ 
ance of these vehicles. 

The amphibian model based on the Brock way is 
pictured in Figure 37. With a design emphasizing 
hull form and eliminating tunnels for appendages, 
its resistance was found to be higher than that for any 
other vehicle model tested. It represents the extreme 
in high resistance for a vehicle designed to fit inside 
the dimensional limits set for optimum land perform¬ 
ance. It may be compared with the DUKW which, 


Figure 38. Stern view of T-86E1 gun motor carriage 

showing how housing propeller in tunnel limits diameter 

and produces high wake fraction and thrust deduction. 

while also remaining within the prescribed limits, 
has a vastly lower resistance because of tunnels and 
shrouding. 

I'he gap remaining between the DUKW and the 
boat, however, indicates that considerable improve¬ 
ment is still needed in amphibious design. 

As a consequence of their high resistance, amphib¬ 
ians have low maximum speeds and extremely high 
fuel consumption, and need relatively large engines. 
Although an engine which will operate satisfactorily 
in a military land vehicle can develop sufficient power 
for marine operation, in the latter it is often required 
to perform over long periods at full power. This in¬ 
creases wear, makes cooling more critical, and re¬ 
quires more servicing. 

Propulsive Coefficient 

Although the higher total resistance of an amphib¬ 
ian calls for greater propeller power, the diameter of 
the propeller is usually limited by the necessity for 
protecting it in both shallow water and land opera¬ 
tion, and the propulsive coefficient of amphibians is 
consequently low. 

Since the hull form as determined by factors de¬ 
scribed above has an inherently high wake fraction 
and a high thrust deduction (Figure 38), a propeller 
in a practicable tunnel cannot fully attain the ad- 
vantage of wake, and reduced pressures on the tunnel 
surfaces forward of the propeller cannot be com¬ 
pletely avoided. This, too, contributes to a low pro¬ 
pulsive coefficient. 

It would be possible to increase this coefficient by 
using retractable propellers or by developing a me¬ 
chanical arrangement which would provide for a 
better propeller tunnel design. The retractable pro- 



C 











192 


AMPHIBIOUS STUDIES 



Figure 39. First pilot model 21/^-ton. 6\6 DUKW in mod¬ 
erate surf. 


peller, however, was excluded because of the added 
exposure to damage, and the use of a standard chassis 
inhibited any significant improvement in tunnel de¬ 
sign. 

Stability 

Because of increased weight for the same water 
plane area, the DUKW has lesser transverse and lon¬ 
gitudinal metacentric heights. Since righting moment 
is a function of both displacement and metacentric 
height, this increased weight counterbalances the 
reduced metacentric height, giving approximately 
the same static stability. 



Figure 40. M-29C amphibious Weasel negotiating storm 
on Lake Michigan. 


The hull form used in the amphibian has improved 
dynamic stability because of its numerous tunnels 
and appendages. These affect the action of the ve¬ 
hicle in rolling, pitching, and heaving in two differ¬ 
ent ways. First, by increasing the effective mass of the 
vehicle in motion (due to entrained water), rolling, 
pitching, and heaving are made more “easy” and mo¬ 
tion due to impact is reduced in amplitude. Second, 
due to the high resistance of tunnel sides and edges 
and of the numerous appendages, especially the 
wheels, velocity of roll and acceleration due to impact 
are both decreased, and the “decrement of oscilla¬ 
tion" or damping is increased. 

Fhc combination of these factors with the higher 
initial mass and the lesser metacentric height in¬ 
creases the period of roll and decreases its amplitude, 
resulting in a substantial improvement in seaworthi- 



Figure 41. DUKWs approaching Normandy beachhead on D-Day, June 6, 1944. 












FUNDAMENTALS OF DESIGN 


I 93 



Figure 42. Pilot model l^-ton, 1\ 1 amphibious jeep en¬ 
tering moderate surl'. 


ness, crew comfort, and cargo safety (see Figures 39, 
40, and 41). 

Surf Ability 

The performance of the amphibians in surf has 
proved satisfactory and consistently superior to com¬ 
parable boats (Figures 42, 43, and 44), and the diffi¬ 
culties have been almost entirely limited to those 
involved with sealing or protection from surf impact. 

Ability to operate in surf is improved by a number 
of factors which thus far cannot be objectively as¬ 
sayed. The reduced freeboard at the ends reduces the 
area of possible surf impact, and as a result the on¬ 
coming or trailing surf frequently breaks on the end 
decks, dissipating its energy without causing exces¬ 
sive pitching. The reduced reserve buoyancy at bow 
and stern also serves to limit the trimming moment 
of large waves and therefore the magnitude of pitch¬ 
ing. The wheels or tracks on an amphibian assist in 
steering and controlling the vehicle when in contact 
with bottom, particularly during landing, and under 
certain conditions make it possible to build up ample 
momentum while landborne to carry the vehicle 
through the surf. The resistance of appendages to 
lateral movement assists in keeping the vehicle in 
proper position to the surf. The amphibian has the 
inherent ability to depart from the surf quickly, re¬ 
ducing the possibility of foundering or damage. 

Protective Sealing 

Flic low freeboard on all amphibious vehicles re¬ 
quires special attention to the protection of necessary 
openings. At the same time, low reserve buoyancy 
demands satisfactory sealing of the immersed hull 
and a reliable bilge pumping system with adequate 
capacity. 





Figure 13. DUKWs operating off Fort Orel, California, in 
surf about 8 feet high. 


In spite of temporary expedients adopted, experi¬ 
ence has proved the necessity of waterproofing the 
engine, control, and electrical components. Field kits 
for waterproofing, including sealing compounds, 
waterproofing sprays, tape, and special greases, have 
been effective only for temporary use and only if 
they are properly used. Permanent amphibians re¬ 
quire factory-waterproofed components, including 
the instrument panel, junction boxes, wiring, and 
engine ignition. 

Since exposure to spray and water is inescapable 
with present designs, corrosion-resistant materials 
must be specified wherever they are needed. Diffi¬ 
culties experienced with exposed brakes indicate the 
desirability of housing brake drums and bands inside 
the hull wherever possible. 

Armor Protection 

No adequate means have thus far been found for 
providing combat amphibians with satisfactory ar¬ 
mor plate protection. The added weight which would 
detract from payload or add to gross weight has ma¬ 
terially restricted its use. 



Figure 44. T-86 amphibious gun motor carriage (left) 
and LVT(A)(4) (right) entering 4- to 5-foot surf during 
tests at Fort Orel, California. 


















194 


AMPHIBIOUS STUDIES 



16” M-24 Light Tank 
Track Block from which 
the 21” Track Shown to 
Left Was Developed 


Figure 45. 21-inch wide track, with parent 16-inch wide track and replaced 12-inch wide track. Weights per linear 
foot of all three are approximately the same. 


Some consideration has been given to providing 
local detachable armor protection to personnel and 
vital parts of the vehicle. A possible solution may lie 
in the use of detachable pontons which give added 
buoyancy and which can be jettisoned when the ve¬ 
hicle is landborne (Figures 21 and 24), but this still 
would have all the disadvantages of a nonpermanent 
conversion and of excess bulk. 

The eventual solution seems to lie in the use of im¬ 
proved materials which would permit lower basic 
weights in the mechanical portion of the vehicle and 
provide greater ballistic protection for the same 
weight in armor plate. 

Driver Vision 

Satisfactory vision for water control usually pre¬ 
sents no serious problems in amphibian design. The 
driver’s steering station must be far enough aft and 
high enough above the water line to provide protec¬ 
tion from spray, sufficient distance to the bow to 
facilitate steering, and a vantage point to give a 
range of vision which will be unaffected by small seas. 

In contrast, numerous difficulties are involved in 
providing vision satisfactory for land operation. 
Driver vision on amphibians is thus far materially 


inferior to that on similar land vehicles, largely as a 
result of the necessary hull end design and the requi¬ 
site low profile. In some cases, “vision blocks” and 
vision cupolas as used in the T-86 amphibious gun 
motor carriage (see Chapter 6) have proved useful on 
combat vehicles. 

Marine Steering 

Maneuverability is particularly important in am¬ 
phibious operations, and a high degree of control is 
essential in entries and exits from the water. Such 
operations, and also operations across country, re¬ 
quire that rudders used for steering must be protected 
by tunnels or so designed that (hey will swing clear if 
they strike an obstacle. 

Marine steering equipment, including control 
from the land steering wheel, quick-acting mecha¬ 
nisms, an inclined rudder post, and an appropriate 
tunnel design, was developed satisfactorily in the 
DUKW amphibious program. 

Loading and Unloading 

1 ’he hull depth required for amphibians and the 
difficulty in sealing submerged hatch covers have 
together interfered with quick loading and unload- 


W-r 











FUNDAMENTALS OF DESIGN 


195 



Figure 46. Artist’s conception of some proposed uses of DUKW: (1) ponton bridge, (2) vehicle ferry, (3) tank wet 
ferry, (3A) tank dry ferry, (4) light freight carrier, (5) heavy freight carrier, and (6) troop carrier. 


ing, particularly on land. An additional restriction 
has resulted from the need for coamings and decking 
at the ends. The stern ramp used on some LVT cargo 
carriers has given some improvement, but new prob¬ 
lems have been introduced by the power-driven ramp 
hoist, swamping over the stern, and the maintenance 
of the ramp seal. 

Mud and Sand Operation 

The use of amphibians both on land and in water 
makes it essential that these vehicles also operate well 
on mud and sand. In general, this requires increased 
tire or track flotation. The M-29C Weasel amphibi¬ 
ous light cargo carrier, with an average unit ground 
pressure of 2 psi, indicates the advantages of increased 
flotation, and at the same time has provided the 
Armed Forces with a vehicle which can successfully 
negotiate soft mud, marsh, swamp, volcanic ash, and 
soft sand. 

Fhe development of a 21-inch wide track for the 
T-86 amphibious gun motor carriage to replace the 
standard 16-inch track represents another approach 
to this problem. The new track, which gives im¬ 
proved operation in mud, uses the pitch and single 
pins of the old design but provides wing extensions, 
holes through the track block base, and a new web 
design. These modifications decrease the weight, as¬ 


sist in clearing mud from the tracks, and reduce the 
unit ground pressure (Figure 45). 

In research on the DUKW, investigations on the 
type of tire and on the effect of tire pressure revealed 
methods for improving the performance of wheeled 
vehicles on mud and soft sand. Large single tires (as 
contrasted with dual tires) with low sidewall stiffness 
together with a central control system enabling the 
pressure in each tire to be controlled from the driver’s 
station, were incorporated, giving the advantages of 
using low pressures for increased flotation on mud or 
sand and high pressures for longer life and lower roll¬ 
ing resistance on hard surfaces. 

Trim of Track-Laying Amphibians 

In order to improve driver vision on land and to 
increase the dynamic freeboard forward, it is desir¬ 
able to provide trim by the stern. With the lim¬ 
itations on hull form as outlined above and the 
necessity for keeping the center of gravity forward 
of the center of the ground contact length for effi¬ 
cient land operation, this trim is difficult to obtain. 

Use of Amphibians 

It has already been emphasized that the best am¬ 
phibians designed to date are inferior to comparable 
land vehicles for land operation and to comparable 

















196 


AMPHIBIOUS STUDIES 


boats for water operation. Obviously, use of the am¬ 
phibian can be recommended only where one unit 
must operate in both environments. Tactical experi¬ 
ence has shown that an amphibian should actually 
be employed when, in the judgment of the command¬ 
ing officer, boats or trucks cannot do the work as 
well, as quickly, or with as few personnel. Among 
these applications are the following: 

]. Landing of shore-based artillery early in the as¬ 
sault on a beach. 

2. Landing operations where landing craft cannot 
operate because of heavy surf or offshore sand bars, 
reefs, or shoals. 

3. Ship unloading over undeveloped beaches or in 
damaged ports. 

4. Reconnaissance which may require deep water 
crossings. 

5. Rescue work over courses where boats and land 
vehicles cannot operate. 

6 . Combat river crossings to establish beachheads. 

7. Raiding operations or surprise attack missions. 

8 . Supply of otherwise isolated units in combat. 

9. Ferrying of other vehicles or troops for dispersal, 
or where suitable facilities for boat disembarking are 
unavailable. 

One concept of the various uses which were pro¬ 
posed for the DUKW is illustrated in Figure 46, 
which shows the vehicles operating as pontons for a 
bridge, and as ferries for troops, freight, tanks, and 
other vehicles. 

The General Problem of Soft Terrain 

No matter whether this country enters an atomic 
arms race or succeeds in suppressing atomic fission as 
a weapon, it will probably remain true that the 
Armed Services should possess large numbers of a 
great variety of amphibious vehicles able to perform 
many different types of missions over mud, snow, and 
quicksand. A good deal of thought has been given by 
the division and its contractors to this general prob¬ 
lem of traversing soft terrain, and at one time or an¬ 
other during the past few years, designs were pre¬ 
pared for vehicles covering a wide range of unit 
ground pressures. The extreme case in this series is 
represented by a jet-propelled plywood vehicle de¬ 
signed for assault at high speed across short stretches 
of extremely soft mucU Next in unit ground pressure 

3 See Section 10.3 in this chapter. 

k See Chapter 5 in this volume. 

t See Chapter 7 in this volume. 


is the Weasel, k next the paddy vehicle, 1 next the 
DUKW with its tires deflated, 111 and finally the tank 
destroyer or high-speed combat vehicle included in 
the Turtle series. 11 

All these vehicles, including the Weasel and the 
DUKW, represent preliminary and very tentative at¬ 
tempts at solutions to the general problem of provid¬ 
ing efficient means for crossing snow, mud, and quick¬ 
sand. This study should be continued on the basis of 
a comprehensive and fundamental program covering 
all the factors involved in the design and use of low 
unit ground pressure vehicles. 

The difficulties of the problem should be clearly 
recognized. In the consideration of a vehicle to be 

O 

used in the Arctic, for example, it should be realized 
that most of the Arctic regions are physiographically 
very old, the rivers meander nearly at grade, the par¬ 
ticle size is small, and the underwater gradient of the 
beaches is flat. In many parts of the Arctic during 
summer, it is impossible for men to get ashore on 
their own feet. The mud Hats of regions of Hudson 
Bay, the mouth of the Mackenzie River, and various 
portions of the Siberian coast have such a high water 
content that they cannot be crossed on foot; they can¬ 
not, in fact, be crossed by the Weasel. 

Similar difficulties would be involved in operating 
a vehicle over the muddy terrain of the mouth of the 
Mississippi, the Louisiana bayous, the Florida swamps, 
and other areas in the Gulf States. 

It is the belief of the division and its contractors 
that improvements in the low unit ground pressure 
technique can be sought in the following general 
fields: 

1. Perfection and modification of existing equip¬ 
ment. Such a program, which could well be carried 
out by Army Ordnance in collaboration with the 
automotive industry, would include such steps as 
modifications in existing models of the Weasel and 
the DUKW. 

2. Development of variations of existing equip¬ 
ment. This type of investigation, which could well 
be conducted by a civilian organization such as the 
Stevens Institute of Technology, should be based on 
fundamental research into the problems surrounding 
low unit ground pressure and woidd include, for ex¬ 
ample, larger Weasels and DUKWs, as recommended 
in Chapters 4 and 5. 

111 See Chapter 3 in this volume. 

11 See Chapter 15 in this volume. 








FUNDAMENTALS OF DESIGN 


197 


3. Development of novel and radical solutions 
Two examples, cited not because it is felt that their 
practicality has been proved but merely because they 
indicate the type of approach involved, include the 
jet-propelled vehicles designed for assault across mud" 
and the vehicle designed with an ultra-soft, hydraulic- 
controlled suspension to enable it to leap obstacles. p 


4. Improved use of vehicles, it appears that the 
value of almost any vehicle can be significantly in¬ 
creased by improvement in indoctrination, organi¬ 
zation, training, operation, and maintenance/ 1 This 
type of improvement should be sought not only for 
any new or improved vehicles which may be devel¬ 
oped but also for vehicles already available. 


o See Section 10.3 in this chapter. n See Section 4.6 in Chapter 4. 

p See Chapter 15. 









Chapter 11 

PONTON BRIDGE REACTIONS 


Summary 

A r the request of the Engineer Board of the U. S. 

- Army Corps of Engineers, an extended study was 
made of ponton bridges typical of those proposed for 
use in military operations. A relatively simple ana¬ 
lytical method was developed for both continuous, 
unarticulated bridges and articulated bridges. a With 
the equations developed, it is possible to determine 
the bridge reactions to loads, and die shear and mo¬ 
ment curves. 1 


>" REACTIONS OF CONTINUOUS 
PONTON BRIDGES 

A continuous, unarticulated ponton bridge of any 
length may be considered as a simpie beam supported 
at 0 (zero) and n (Figure 1). It may be investigated for 


eb-ebi cb 


n-i 


Figure 1. Continuous ponton bridge without articulation. 


one or more loads acting downward and a series of 
generally upward forces, the reactions of the pontons, 
under all of which it must meet deflection conditions 
to give a consistent solution. Under load (Figure 2), 


/ORIGINAL BEAM AXIS 


^ ( ie ,WITHOUT LOAD) 




2 ^ 


Figure 2. Ponton bridge with load. 


the end pontons will go down and the assumed simple 
beam will deflect below the line joining the ends. At 
each interior ponton, a force will be applied which 
will lower that ponton, raise the end pontons, and 
cause the beam to deflect above the line joining the 
ends. Fhe distance that a ponton goes down must 
therefore equal the difference between the amounts 


the corresponding point on the beam goes down due 
to the loads and up due to the ponton reactions. 

For convenience it is assumed that the ponton reac¬ 
tion is a force at the center of the ponton and that all 
horizontal sections through the ponton have the same 
area. Idle displacement C per foot depth of ponton 
equals the product of this area (square feet) and 62.4 
(pounds per cubic foot) and is expressed in pounds 
per foot. 

Let a load P act at point b (distance kL from 0) on 
a beam length nL, supported by pontons at 0 and n 
(Figure 3). At a point a (distance fL front 0), it is de¬ 



sired to find « 1 a 2 , the distance that a point on AB, the 
straight line joining the beam ends, is below A Ah* 
the original unloaded position of the line. The por¬ 
tion of the load that goes to the ponton at 0 is 

nL — kL p 
nL 


and, therefore, 


A,A 


n — k 
~nC~ 


P. 


Similarly 


B, B 


kP 

nC 


4’hen 


a \ a 2 


(n - k)P f r (n - k)P kPl 
nC n L nC nCj 



a This investigation was conducted by the Drexel Institute of 
Technology, Philadelphia, Pa., under OSRD contract OEMsr-41. 



k-i + M 

n 


11)8 














































REACTIONS OF CONTINUOUS PONTON BRIDGES 


199 


In the same way, an interior ponton reaction R at 
a distance xL from 0 will at n raise AB an amount 



Next it is desired to find the distance a 2 a (Figure 3) 
which P and R cause a to deflect from line AB. (The 
computation will be made by the “conjugate beam” 
method, but the same restdt would be obtained by 
any other method for computing deflections.) Load 
P causes the reactions and moment curve of Figures 
4A and 4B. The conjugate beam and its load are 
shown in Figure 4C. Because of this load, the right 
reaction is 


= — nl FF 4~ k)L 

2 El n 3 nL 

= PL - k(n 2 - A 2 ) 

6EI n 


Then 


a.,a 


PLr k (n 2 — A 2 ) 

6EI ji { n 

_ hn - f U FL ~ /) (” ~ 
n ^ El n 3 


PL* p(n 2 - A 2 ) (n -/) _ k(n - ff 
6E1 1_ n n 


PL 3 A(» - /) [(»- - A 2 ) - (>i - /)*] 
6E1 n 


PL* k(n - /) (2 nf — A 2 — / 2 ) 
6FJ n 


In the same way it may be shown that, if P is ap¬ 
plied to the right of a, 


a.,a 


PL* f(n - k) (2 nk - f 2 - A 2 ) 
6 El n 



If there is a ponton at a distance fL front 0 and this 
ponton has a reaction R f , b then by using the values 
which were derived above, it is possible to write the 
following equation: 


2 fkl 




PL* k (n - f) (2 nf - A 2 - / 2 
+ * 6EI n 


PIS 2 f 2 (n - /) 2 
^ 6EI n 


^PL* f(n - A.) (2 nk - f 2 - A 2 ) 
f "6EJ n 


* nc\_ 


n-x-f+ 




_ N 


RJA s(n - /) (2 nf - .v 2 - f 2 ) 
6EI n 


[ A term tor each 
load. 

TA term for each 
load applied to the 
Lleft of /. 

t A term if a load is 
applied at /. 

[ A term for each 
load applied to the 
right of /. 

[ A term for each 
interior ponton in¬ 
cluding /. 

r A term for each 
interior ponton to 
Lthe left of f. 


] 

] 

] 

] 

] 

] 


and if P is applied at a, 


a oft 


PL* 2 f 2 (n - f) 2 # 
6E1 n 


R f L 3 2 f 2 (n - /) 2 
6 El n 


[ One term. 


r K.IA f(» ~ r) (2 nr - f 2 - r 2 ) 
^ 6 El n 


rA term for each 
interior ponton to 
Lthe right of /. 


Similar upward deflections occur when the reac¬ 
tion R is applied to the left of a, to the right of a, 
and at a. 

Finally, due to a reaction R, a ponton will go down 
a distance R / C. 



bA subscript (for example, x) after a ponton reaction indi¬ 
cates that the ponton is at a distance xL from 0. 



























































PONTON BRIDGE REACTIONS 


‘.CO 


For convenience in computing, multiply all of the 
foregoing terms by nC and let 


CL 3 

6EI 


= H. 


In any case the solution will be made for a known 
load or loads in a fixed position. Hence the terms con¬ 
taining P will be known numbers, and the unknowns 
in the equation will be the interior ponton reactions. 
By placing all unknowns to the left of the equals sign, 
it is possible to write the following equation: 




+ i R,H [s(n - /) (2 nf - s"- - /*)] 


■t in (1) for eachq 
irior ponton, in- 

ling /. J 

for eachU 
nton to 

f. J 


A term (2) for each" 
interior pout 
_the left of /. 


+ R f H [2 f 2 (n. — f) 2 ] [ One term (3). 

+ nRf [ One term (4). 

r A term (f 

+ 2 \R,H f(n — r) (2 nr — / 2 — r 2 )] interior | 

L v Lthe right 


A term (5) for eachq 
ponton to 
right of /. J 


p[n-k-i+ 2 f] [^r <6)for “ ch ] 

] 


t A term (7) for each 

™ie d >o 'I" 


+ PH [2 f-(n - f) 2 } 




/• 

term (8) if a load 
pplied at /. 


t A term (9) for eachq 

loa j , t a PP / lie(1 10 the J 


Just as the foregoing equation has been written for 
the ponton reaction of /, a similar equation may be 
written for every interior ponton. This will give a 
group of equations in which there are as many un¬ 
knowns as there are interior pontons. Since there will 
be this same number of equations, a solution of these 
simultaneous equations will give the numerical values 
of the interior ponton reactions. Following this, the 
values of the ponton reactions at 0 and n may be 
found by statics, and the shear and moment curves 
may be drawn for the structure. 


1111 Solution of Equations 

A number of examples are solved here to show the 
application of the method. 


Example 1. Find the reactions and draw the shear 
and moment curves for the structure and load shown 
in Figure 5. 



Figure 5. Structure and load. Example 1. 


Solution: Here n = 2 and k = 0. By using the equa¬ 
tion above, an equation will be written for the 
only interior ponton reaction—that is, for / = 1. In 
this instance there will be values corresponding to 
terms (1), (3), (4), and (G). Normally term (7) would 
also appear, since it involves a load to the left of /. 
Here, however, it equals zero, since zero is the value 
of k. 

R, (2 — 1 — 1 + 2 'g' - 1 -) + RiH(2 • l 2 • l 2 ) + 2 R, 

= P( 2 — 0 — 1 +-g-/ 

R, + 2 HR l + 2R l = P, 

$R X + 2HR, = P. 

This is as far as the solution can be carried until a 
value is assigned to H. The following will be assumed: 

L = 1G ft, 

E = 1,500,000 psi, 











































REACTIONS OF CONTINUOUS PONTON BRIDGES 


201 


/ - 1I [n-4-( 7 T)’]- 2 - 21,in - 4 - 

C — 160 sq ft • 62.4 lb per cu ft = 10,000 lb per It. 


Then H 


CL* 
6 El 


10.000 • 16 3 

2211 

6 • 1,500,000 • 12 2 • 


= 0.296. 


Example 2. Solve the structure of the previous ex¬ 
ample when the load is placed at the middle of the 
first span as in Figure 6. 

Solution: For every two-span structure, the left side 
of the equation is constant. Now, k = i/ 2 . Therefore, 

3.592 R, = P f2 — l/ 2 - 1 + 2 ' - I, ---] 

+ PH [1/2(2 - 1) (2 • 2 • 1 - i/[ - 1)] 


Note that it has been necessary to express E and 1 
in foot units since C and L are in foot units; also that 
// is a dimensionless number—that is, all units cancel. 


Ill 

it 


ft 3 



= P + —HE 

O 

= P + ii(0.296)/ J 

O 

= 1.407 P. 


3 R l + 2(0.296)/?! = P 

n '-sm = °' 2S0 p t 


By 2A/ = 0 about 0, Z? 2 = 0.140 P | (i.e., down) 
By 2 V =0 R () = 0.860 P f 



/?! = 0.392 P, 
II.. = 0.054 P, 
/?„ = 0.554 P. 


Example 3. Solve the structure of the previous ex¬ 
ample when the load is placed over the center ponton 
as in Figure 7. 





Figure 6. Structure and load. Example 2. 


Figure 7. Structure and load. Example 3. 




































































202 


PONTON BRIDGE REACTIONS 


Solution: Here k = 1. Therefore, 

3.592 Ri = p (2 - 1 - 1 + 2 ' 

+ PH[2 ■ l 2 (2 - l) 2 ] 

= P + 2HP 
= 1.592 P. 

.-. P 1 = 0.444 P, 
i? 0 = K 2 = 9.278 P. 

Example 4. Find the reactions and draw the shear 
and moment curves for the structure and load shown 
in Figure 8. Assume that H has the same value as in 
the previous examples. 

Solution: Here two equations must be written, one 
for / = 1 and the other for / = 2. For / = 1 

ft, [s - ] -1 + 

+ R X H [2 • 1 2 (3 - l) 2 ] + 3 R x 
+ RoH [1(3 — 2) (2 * 3 • 2 — 1 - — 2 2 )] 

= P ^3 - 0 - 1 + 2 * g-- — , 

+ 8 HR, + 3 R, + 1HR , = 2 P, 

3 5 

-yi?! + 8 HR, + |p 2 + 1HR 2 = 2 P. (1) 

For / = 2 

t 2 . 9 • 11 

3_ 1 _ 2 + ^_I] 

r 9 . 9 • 91 

+ P 2 [3 - 2 - 2 + ——=—-J 

+ R X H [1(3 - 2) (2 • 3 • 2 - l 2 - 2 2 )] 

+ R,H [2 • 2 2 (3 - 2) 2 ] + 3 R 2 

/ 9.9. f)\ 

= P ( S _ 0-2 + ^-»> 

+ \r 2 + 1HR, + 8 HR 2 + 3 R 2 = P. (2) 



Therefore, since H = 0.296 


7.035 

Pi 

+ 

3.405 R 2 = 

= 2 P, 

(!') 

3.405 

Ri 

+ 

7.035 R 2 = 

= P, 

(2') 

7.035 

Ri 

+ 

14.500 R, 

= 2.064 P. 

(2'0 




11.095 R, 

= 0.064 P, 

(2" - V) 




r 2 

= 0.006 P. 


7.035 

Ri 

+ 

3.405 (0.006)P = 2P, 



R l = 0.282 P. 


The values of R 0 and R :i may be found by use of the 
equations %M = 0 and XV = 0. 

Example 5. Find the reactions and draw the shear 
and moment curves for the five-span structure due to 
two loads as shown in Figure 9. 

Solution: The complete solution is shown on the 
insert with Figure 9. Note that in the section labeled 
Eormation of Equations, there are four areas which 
are bounded by heavy solid lines. The computation 
within these areas relates to every regular five-span 
structure and need never be made again. Further¬ 
more, in this same section there are four areas and in 
the section Solution of Equations another area—all 
bounded by heavy dashed lines. This much of the 









































n =5 



H = 0.296 



Figure 9 




SOLUTION OF EQUATIONS 


Ei 

q. /?i 

r 2 

*3 

^ Absolute 

— -10 

Check 




1 

17.87 

16.12 

14.04 

8.41 

30.83 

87.27 




2 

16.12 

28.91 

22.53 

14.04 

43.40 

125.01 




3 

14.04 

22.53 

28.91 

16.12 

39.95 

121.55 




4 

8.41 

14.04 

16.12 

17.87 

24.61 

81.05 




r 

1 

0.902 

0.787 

0.472 

1.725 

4.886 




2' 

1 

1.794 

1.398 

0.872 

2.693 

7.757 




3' 

1 

1.605 

2.060 

1.148 

2.846 

8.659 




4' 

1 

1.670 

1.917 

2.126 

2.926 

9.639 

2' — 

1' 


a 


0.892 

0.611 

0.400 

0.968 

2.871 

3'- 

r 


b 


0.703 

1.273 

0.676 

1.121 

3.773 

4'- 

r 


c 


0.768 

1.130 

1.654 

1.201 

4.753 




a 


1 

0.685 

0.448 

1.086 

3.219 




b‘ 


1 

1.811 

0.962 

1.595 

5.368 




c 


1 

1.472 

2.153 

1.564 

6.189 

V - 

a 


d 



1.126 

0.514 

0.509 

2.149 

c — 

a 


e 



0.787 

1.705 

0.478 

2.970 




d' 



1 

0.456 

0.452 

1.908 




e 



1 

2.167 

0.607 

3.774 

e — 

d' 


f 




1.711 

0.155 

1.866 




f 




1 

0.091 

1.091 


Eq. 

*1 

r 2 

Rs 

-1 

r, : 

r 

Absolute 

-10 

d' 



r 2 

+ 0.041 


0.452 



r 3 



0.411 

a' 


r 2 

r 2 

+ 0.282 

+ 0.041 

1.086 

0.763 

r 


+ 0.688 

+ 0.324 

+ 0.043 


1.725 

Ri 





0.670 


Equation4. ^ -- Equations. ^ " ' Equation 2. - Equation 1. 


FORMATION OF EQUATIONS 



[ = 3.4/?i] 

+ /? 2 (5 2 1 + 2 *J‘ 2 ) 

[= 2.8/?,] 

+ R,(5 - 3 - 1 + 2 - ) 

[= 2.2/? s ] 

+ ^(._4_, + L^±) 

[= 1.6/?4 ] 

4 1 >+ 5 2 ) 

[= 49.6] 

+ /?,//(2 -1-16) 

[= 32///?!] 







+ J6«(l .|)(2-5-|-!-|) 

[ = 658 H J 

+ 5/?! 

[= 5/?, ] 

+ /? 2 //[l -3(2-5-2~ 1 -4)] 

[= 45///? 2 ] 

+ /? 3 //[l - 2(2-5-3~ 1 -9)] 

[= 40///? 3 ] 

+ /? 4 //[l • 1(2-5 - 4 - 1 - 16)] 

[= 23///? 4 ] 

+ 4 ( 5 8 '+ 5 8 ) 

[= 10.3] 









+ 4 H[l.|(2.5.«- 1 -M)] 

[ = 180//] 

+ 8.4/?x -4- 32HZ?! 

+ 2.8/? 2 + 45///? 2 

+ 2.2/? 3 + 40///? 3 

+ 1.6/?4 + 23 HR 4 


= 59.9 + 838// 

1 

^^ +17.87/?i 

+ 16.12/?2 

+ 14.04/?3 

+ 8.41/? 4 

-,- 

— 308.3 



[ = 2.8/?j ] 

+ /? 2 (5 2 2 + 2 ' 2 ’ 2 ) 

[= 2.6/? a ] 

+ /? 3 (5 — 3 — 2 + 2 * 2 * 3 ) 

[= 2.4/?,] 

+ /?4^5 — 4 — 2 + 2 ‘ 2 ’ 4 ) 

[= 2.2 /? 4 ] 

>4 §~ 2+ 5 2 ) 

[- 43.2] 

+ /?,// [1 *3(2*5*2 — 1 -4)] 

[=45///?!] 







+ 16H[|-s(2-5.2-|- 4 )] 

[ = 990// ] 



+ /? 2 Z/ (2*4*9) 

[=72 HR 2 ] 





+ 4 ( 5 8 2+ 5 8 ) 

[= 10.1] 



+ 5/? 2 

[- ] 

+ R 3 H [2 • 2 (2 • 5 • 3 — 4 — 9) ] 

[= 68///? 3 ] 

+ Z? 4 //[2 • 1 (2 • 5 • 4 — 4 — 16)] 

[= 40///? 4 J 

+ 4 »[*-T(*- s -T- 4 -if); 

] [ = 296 H ] 

+ 2.8/?! + 45H/?i 

+ 7.6/? 2 + 72///?2 

+ 2.4/? 3 + 68///? 3 

+ 2.2/? 4 + 40///?4 


= 53.3 + 1286 H 

| 


|- — -■■■■ ■■■ 








1 


—► + 16.12/?, 


+ 28.91/? 2 


+ 22.53/? a 


+ 14.04/? 4 

rr 434.0 


/?,(5 — 1 3 + 2 'I' 1 ) 

[= 2.2/?!] 

+ /? 2 (5 - 2 - 3 + — 

[= 2.4 R a ] 

+ /? 3 (5 3 3 + 2 * 3 ' 3 ) 

[= 2.6/?,] 

+ /? 4 ^5 4 3 + 2 * 3 ' 4 ) 

[= 2.8Z? 4 ] 

,# (* i- s+ 5 2 ) 

[= 36.8] 

+ /?,//[! - 2(2-5-3- 1 -9)] 

[=40///?,] 

+ /? 2 // [2 • 2 (2 • 5 • 3 — 4 — 9) ] 

[= 68///?,] 





+ 16//[J- 2^2.5 • 3 — | — 9^] 

[ = 900//] 





+ /? 3 //(2 *9*4) 

[= 72///? 3 ] 



+ 4 ( 5 8 S+ 5 8 ) 

[= 9.9] 





+ 5/? 3 

[= 5/?, ] 

+ /? 4 //[3-1(2-5-4-9- 16)] 

[= 45///? 4 ] 


[ = 292 H ] 

+ 2.2Z?i + 40///?i 

+ 2.4/? 2 + 68//Z?2 

+ 7.6/? 3 + 72///? 3 

+ 2.8/? 4 + 45//Z?4 


p 46.7 + 1192// 

—+ 14.04/?i 

+ 22.53/? a 

+ 28.91/? 3 

+ 16.12/?4 

1- 

— 399.5 


R,( 5 -l-4+il|-LL) 

[= 1.6/?,] 

+ Rl ( 5 _ 2 . 4 + L^i) 

[= 2.2 /?,] 

+ /? 3 (5-3 4 + 2 * 4 * 3 ) 

[= 2.8/?,] 

+ R4 (5_ 4 _ 4 + 2 -4.4) 

[= 3.4/? 4 ] 

,6 ( 5 1 4+ 5 2 ) 

[= 30.4] 

+ /?,//[! • 1 (2 * 5 • 4 — I - 16)] 

[= 23///? t j 

+ /? 2 //[2 • 1 (2 • 5 • 4 — 4 — 16)] 

[= 40///?,] 

+ R 3 H [3 • 1 (2-5*4-9- 16)] 

[= 45 ///?,] 



+ 16//[|- 1^2-5-4-| - 16)] 

[ = 522// ] 







+ /? 4 //(2 -16-1) 

[= 32///? 4 ] 

+ 4 ( 5 8 4+ 5 8 ) 

[= 9.7] 







+ 5/? 4 

[- 5/? 4 ] 

+ 4 H[f.,(2.5. 4 -,6-^)] 

[= 174 H] 

+ 1.6/?! + 23///?i 

+ 2.2/? 2 + 40///?2 

+ 2.8/? 3 + 45///? 8 

+ 8.4/? 4 + 32///? 4 


- 40.1 + 696 H 












^ + 8.41/?, 


+ 14.04/?2 


+ 16.12Z?3 


+ 17.87/?4 

I 

— 246.1 




























































































































































































































































































Reactions of Ponton Bridges (without articulation) 


Method of Solution: Letting f vary from 1 to n — 1, write one equation of the 
form shown above for every interior reaction. The unknowns in these equations will 
be the values of the interior reactions and there will be as many equations as there 
are unknowns. Solve this set of simultaneous equations for the values of the interior 
reactions. Then use the equations 2Af * 0 and XV — 0 to determine the end 
reactions. With all reactions known, shears and moments may be found throughout 
the structure. 


Consider a bridge of any length as a simple beam supported at 0 and n. Due to a 
load P applied at a distance kL from 0, a straight line joining the beam ends will, at 
a distance fL from 0, be an amount a x a 2 below the reference line (i.e., the original 
position of the beam). (C is the load to cause a ponton to settle a unit distance.) 

In like manner, an interior ponton reaction, R x , at a distance xL from 0 will cause 
an upward motion a x a 2 . 

If* </ 


Due to a load P at a distance A£ from 0, there will be a deflection a.,a 
below the straight line joining the beam ends and at a distance fL from 0. 


If A = / 
If A > / 


Similarly, a ponton reaction R will 
cause a deflection a.,a at a distance fL 
from 0. 


If R, is the reaction and sL its distance 
from 0 where s < f 

If R f is the reaction and fL its distance 
from 0 

If R r is the reaction and rL its distance 
_ from 0 where r > / 


Also, under a reaction R f , the ponton at a distance fL from 0 will go down a 
distance 8. 


Case I. Both ends on pontons. 


nL 


fL 


KL 


dp dp -- dmdbfe M-^ 


2 f 

nL 


n*l 


f L 


• kL - 



p 

«- 

-—, 


--—' 


Figure 10 


a ' a >- 

- - p M k{n - m T k, ~ n ] 


a 2 a 


a.,a 


PL»j- 2/»(n-/)« j 


6 El 


PL* [ (n-k)f(2nk-k*-P) 


6 El 


R.L> r*(n-/)(2n/-i»-f) 


f a«a 

6 El L n 


a 2 a 

6£/ L n J 

_ R r L* [ f(n - r)(2nr - r* - p) ^ 


6 El 


8 - Si 

C 


Case II. One end on a fixed support. 


Qk. 


f L 


KL 





I 2 f n-1 

n L 


f L 


• kL • 

P 






a x a 2 


a 2 a 


Figure ll 


Pfk_ 

Cn 3 

R.f* 

Cn 2 

PL?Vk{n - ftGnf-k*-]*)' 


PL? f 

6 £/[_ 




PL? f(n - A)/(2nA - k 2 — / 2 ) 
n 


pl? r 
fl2 " *6Ell 

R,L* r x(n-/)(2n/-s 2 -/ 2 ) j 


6£/ | 

L 


-2/2^ - /) 2 ] 

6£/ 1 

. n J 

R r I? 1 

-f(n-r)(2nr-r*-p) 

6£/ | 

n 

«/ 


C 



Case III. Both ends on fixed supports. 


JlL 

f L 


KL 

p 

i 1 

L ^ 


fT - —7 


□ CPifP 



nL 

f L 

“I 

r ~=^L 

« kt H 

P 

a. 

1-H 




a 


Figure 12 


a x a 2 - 0 


a x a 2 = 0 


a 2 a 

a, a 


PL* [ (n- k)f(2nk - k* - P) 


6£7 L 


n 

j 

R*L* I 

rs(n - 

f)(2«f- 

- * 2 - fn 

6£/ | 

. 

n 

J 

P//4I 

[2/ 2 (n 

-/H 


6A7 | 

L n J 


P r /4 1 

r/(»- 

r)(2nr - 

- r 2 - / 2 ) 1 

6£/ | 


n 

j 


R, 


Now 2a +2c 4 d + S e —2b — 2 f — g — 2 h — i 
or. Sb+Sf + g+ 2h+i=Xa+Sc + d+ Se 

That is, as / varies from 1 to n — 1 there will be: 
a' A term like this for every reaction, including /. 

b' A term like this for every interior reaction to the left of /, distance sL from 0. 

c* One term like this. 

d' One term like this. 

e' A term like this for every interior reaction to the right of /, distance rL from 0. 

f A term like this for each load. 

g* A term like this for each load for which k < f. 

h' A term like this for a load k =/. 

i' A term like this for each load for which k > /. 


Z &(■—/+*) 

V ^p(r»-/)(2n/-^-m 
^ A 6£/ L n J 

R t L*L2p{n-f)n 
6EI L n J 


yRrfx 

A Cn 2 

Y*.£»p(n 

A 6£/ L 


-/)(2»/-s 2 -/ 2 )- 


4 


R f L* r 2p(n — /) 2 ~| 
6EI L n J 


R, 


4 


STRrl * r 

A 6ei L 


f(n - r)(2nr - r 2 


“] 


+ VW[ *(n-/)(2n/-^-f) ] 

+ PL*r 2p(n - f)n 
HEI L n J 

+ yPL* nn-k)f(2nk-k*-m 

A 6£/L n J 


4 Si 

C 

. Y /? r £ 3 [- /(n-r)(2nr-t 2 -m 

A 6£/ L n J 

ACn 2 

Y PL* [ k(n — f)(2nf — A 2 — Z 2 ) "! 

A 6£/ L n J 

PL? f 2P(n - /) 2 1 
'6 El L n J 


Z PL? T 

6£/ L 


(n — A)/(2nA — k 2 — p) 
n 


V 7?,£ 2 r s(n-/)(2n/-s 2 -/ 2 ) -l 

A 6£/ L n J 

+ /g/£ s r2 /«(w-/)n 

6£/ In] 

+ § 

+ V ^ | 7(» - r) (2nr - r 2 - Z 2 ) j 


P/4 fA(n — f){2nf — A 2 - 


Z PL a r 

6£/ L 

+ P£ 8 f 2/ 2 (n-/) 2 1 

6£/ L n J 


fl] 


(n — k)f(2nk — A 2 — Z 2 )’ 


CL 3 

Multiply all terms by Cn and let H = 

Finally, there will be: 

a * A term like this for every reaction, including /. 

b~ A term like this for every reaction to the left of /, distance sL from 0. 

C One term like this, 

d” One term like this. 

e" A term like this for every interior reaction to the right of /, distance rL from 0. 

f" A term like this for each load. 

g" A term like this for each load for which A < /. 

h" A term like this for a load A =/. 

i" A term like this for each load for which A > /. 


Y R ’(r- x -t + ir) 

+ Y j R.H[s(n-f)(2nf-s*-P)) 
4 R f H[2p{n — f) 2 ] 

4 R f n 

+ £* r H[/( n -r)(2r,r-r 2 -/ 2 )] 
+ ^TpH[A(n-/)(2n/-A 2 -/ 2 )] 

+ PH[2/»(n-/) 2 ] 

+ ^PH[(n - k)f(2nk - A 2 - />)] 


Z^ 

4 ^ /?,// [r(n — f)(2nf — s 2 — p)] 
4 *,W[2/*(»-/)«] 

4 

+ ^« r H[/(n - r)(2nr - r 2 - /»)] 

+ ^PH[*(«-/)(2 n /-* 2 -/ 2 )] 
+ PH[2f(n-/) 2 ] 

+ ^ PH [(n - k)f(2nk — k 2 — Z 2 )] 


^P.H[j( n -/)(2n/- I 2 -p)] 
+ ^,H [2/ 2 (n — /) 2 ] 

4 P/n 

+ ^ U(n - r)(2nr - r 2 - / 2 )] 


^P//[A(n-/)(2n/-A 2 -/ 2 )] 
4 P// [2/*(n — /) 2 ] 

4 P//[(n - A)/(2nA - A 2 - f 2 )] 


i 




































































































































































































REACTIONS OF ARTICULATED PONTON BRIDGES 


203 


sheet relates to this particular structure and is inde¬ 
pendent of the load. In other words, to investigate 
a structure for an additional position of the loads 
would necessitate the repetition of perhaps one-third 
of the work represented by this figure. 0 

The foregoing equations cover the situation in 
which all support is furnished by pontons. There are 
two other situations, however, that occur frequently— 
one in which one end of the structure is on an un¬ 
yielding support, and another in which both ends are 
on such supports. The equations for all three of these 
cases are given on the insert with Figures 10,11, and 12. 

It should be noted that the derivations obtained 
here are based on the following assumptions: 

1. The balk act as continuous beams. 

2. The support at a ponton may be considered as a 
point support. 

3. The righting moment due to the rotation of a 
ponton may be neglected. 

4. Ponton displacement and ponton reaction are 
directly proportional to each other. 

i»2 REACTIONS OF ARTICULATED 
PONTON BRIDGES 

For certain combinations of ponton properties and 
bridge stiffnesses, it has been found necessary to per¬ 
mit an amount of articulation in the joints between 
the rafts which make up the structure. The joints are 
so arranged that some degree of motion must take 
place before they can transmit moment. Frequently 
the arrangement is such that the joints transmit no 
moment or, when closed, positive moment, but are 
unable under any condition to transmit negative 
moment. 

The three-raft structure in Figure 13 may be con¬ 
sidered as an example. Figure 13A shows the struc¬ 
ture without load. If a small load P is placed over the 
center raft, that raft will be displaced downward 
(Figure 1313), but the adjoining rafts will simply 
rotate without supporting any considerable load. 
This rotation will continue until the joints between 
the rafts lock. 

Until this locking occurs, the outer reactions equal 
zero. Any further load will be shared in some ratio 
among the three reactions. 

For convenience, the sketch of Figure 13C will be 

c Technical literature records many possible methods for the 
solution of equations. Obviously any other method desired by 
the computer might be substituted in Section 11.1.1. _ 


considered equivalent to that of Figure 13B. except 
that in Figure 13C it is assumed that the load has 
been increased until the joints lock (R 2 still equals 
zero). This will give the maximum reaction R lm 
which one raft alone can support. As shown, the 
elastic curve of the structure will have at the joints 
an abrupt angle a. The magnitude of this angle, or 
the amount of articulation, will depend on the 
construction. 

As before, let L equal the raft length in feet and C 
the displacement of a ponton or raft in pounds per 
foot. In Figure 13C, it will be seen that the center 
ponton has been submerged an amount CaLj 2, for 
which the symbol K will be used. Hence, 


Seven Rafts Acting, Maximum 

A number of additional structures may now be in¬ 
vestigated for a single center load. I he greatest odd 
number of rafts acting will be taken as seven, that is, 
a nine-raft structure with the outer reactions equal to 
zero. From the center, the reactions for this case will 
be designated R 1 _ lm , /G- 7 m> etc. (See Figure 14.) By 
the geometry of the figure, it may be shown that due 
to an angle of articulation a, the amounts by which 
successive points of reaction in each joint lie above 
the point of reaction at the center are, as indicated on 
line XX, aLj 2, \aL\2, 9aL/2, and 16«L/2. 



Figure 13. Articulated ponton bridge with load. 









































204 


PONTON BRIDGE REACTIONS 



Figure 14. Seven rafts acting, maximum. 


Added to the offsets due to articulation, there will 
he deflections due to load. For example, the two loads 

Ro _ 7m alone will cause a symmetrical moment curve 

(one-half shown on line B), and, as may be shown 
by any method of computing beam deflections, will 
produce upward deflections above R x , at the points 
of application of R 2 , R 3 , R±, and R 5 = ( 0 ) of 

2R 2 _ 7m L/6EI, 5 R 2 _ 7m L/6EI, 8 R 2 _ 7m L/6EI, and 
\]R 2 - 7m L/6EL Similarly, the moment curves and 
deflections produced by _R 3 _ 7m and R 4 _ 7m are shown 
on lines C and D. It is understood that the offsets due 


to articulation and the three sets of deflections are 
acting simultaneously. 

The difference in the reactions R 4 __ 7m and R 2 —i m 
will be C times the difference in the amounts by which 
the two pontons are submerged. That is, by again 
letting CL S /6EI equal H 

R-l-lm ~ R2 — 7m 

2i? 2 _7 OT L 3 5i? 3 _ 7m L 3 8/? 4 — 7 ot L'* \ 

2 6 El 6 El 6 El ) 

= A + 2f//? 2 _ 7m + 5HRo_ lm + MR 4 _ 7m . 

































































REACTIONS OF ARTICULATED PONTON IlKIDCES 


205 


In the same way 

R 1 — 7m — ^3 — 7 m 

_ r (A aL 5R 2 _ lm L- < 1 6R 3 _ 7 JJ 2iR,., m L‘\ 

\2 ^ 6 El + 6EI + 6EI ) 

- 4K + 5HR.._ lm + 16 HR s _ lm + 28 

^ 1 — 7 »i ^ 4 — 7 m 

_ r (9aL 8R,_ lm L* 28R ;1 _ 7m L° , 54// 4 _ 7m /A\ 

■ °v~r + e ei + — m — + — m—) 

= 9A' + 8 HR 2 _ 7m + 28W/( 3 _„„ + 54 HK 4 _ 7 „„ 

Rl — lm 11 

_ r /16a£ 11A 2 _ v „Z.h 40K 3 _ J „Z. i > , 81A 4 _ Im /J\ 

“ A~ + 6E?- + -6E/- + -6 Tl - ) 

= 16 K + 11 + 40HK 3 _ 7 ,„ + 81 HR,_, m . 

Transposed, these four equations become 

«i-7,n - (1 + 2 H)R,_ 7m - 5HR 3 _ 7m - 8 HR 4 _ Tm 

= K, 

Ri-im - oHR,_ lm - (1 + ]6 H)R,_ lm -28 HR 4 _ 7m 

= 4 A', 

- 8Hi? 2 -7m - 28///7 3 _ 7m - (1 + 51//)A 4 _ 7m 

= 9A, 

«l-7m - 1 - 40 ///? 3 _ 7ot - 81H7T_ 7) „ 

= 16A. 

Since // and A are constants with values fixed for any 
given bridge being investigated, it is apparent that 
four simultaneous equations with four unknowns 
(the values of the reactions) have been obtained. A 
solution yields the following values: 

„ _ A(16 + 252 H + 256 H- + 41 H s ) 

Rl — lm ~ 


R-i — 7 m 


A(7 - 42 H + 6// 2 ) 

" 1 - 60 H + 42 H- - 3// :! 


R'2 — 7 in 


R 


3 — 7 m 


1 - 60 H + 42 H 1 - 3 H 3 


A(15 + 166/7 + 73//-) 

1 - 60/7 + 42/7- - 3/7 3 ’ 

A(12 + 29/7 - 30//2) 

1 - 60/7 + 427/2 - 3/7‘ 5 ’ 


1 he maximum load P lm which seven rafts may 
carry without becoming the nine-raft case may be 
obtained from the equation 

P- m = R-l — l m + 277 2 — 7m + 277 3 _ 7)H + 2R 4 _ 7m . 

Substituting the values which have been obtained 
from the reactions, 

p A (84 + 558/7 + 354/7 2 + 41/7 3 ) 

7 ”' 1 - 60/7 + 42/7 2 - 3/7 3 


Seven Rafis Acting, Not Maximum 

This case covers seven rafts supporting the load, 
but the load is not great enough to close the next 
joints. The first three equations for this case will be 
the same as the first three for the seven-raft-maximum 
case. The fourth equation is 

Ri-I + 2/T_ 7 + 2/? 3 _7 + 2A 4 _t = p. 

That is, the four equations which will permit deter¬ 
mination of the reactions are 

//,_- —(H- 2H)R.,_- t — 5HR s _ 7 — 8HR 4 _ 7 = A, 

77, _ 7 — 5/7T?2_ 7 — (1 + 16/7) T?3_ 7 —28/7 T7 4 _ 7 = 4A, 

T7 1 _ 7 — 8 / 7 /? o _ 7 — 28 / 7T7 3 _ 7 — (1 4 - 54 / 7)/? 4 _ 7 = 9A , 

77,-t + 2/T_ 7 + 277 3 - + 2T7 4 _ 7 = F. 

Solved, these yield the values 

77,-7 

_ P(l + 72/7+ 13l/7 2 + 26/7 3 ) + A(28-26/7+ 2T7 2 ) 

7 + 196/7 + 1937/2 + 2 6// 3 


_ P(1 + 57/7 + 46// 2 ) + A(21 + 16/7 - 4/7 2 ) 
Xl ’ -7 7 + 196/7 + 193//2 + 26T7 3 

_ P(1 + 23/7 - IS// 2 ) + A(65/7 + 14/7 2 ) 

:! - 7 7 + 196/7 + 1937/2 + 267/3 

P(1 - 18/7 + 3/72) _ A( 35 + 68/7 + 1 1/7 2 ) 
4-7 7 + 196/7 + 193//2 + 26/7 3 
























PONTON BRIDGE REACTIONS 


206 


Five Rafts Acting, Maximum 

Again use may be made of Figure 14, with the 
modification that A 4 _ 5 = 0, and line D consequently 
is meaningless. Proceeding as before, 


- *2- 


-c(f 


aL , 2, 5/?q_ 5 ,„L 3 


+ 


6£/ 


+ 


6 El J 


= K + 2HR,_ 5m + 5HR 3 _ 3m , 

-^3 — 5 m 

/4flL 5 £ l ._,-„„L 3 16fl 3 _ 5 ,„£ 3 \ 

V 2 6£/ ^ 6£/ / 

= 4 A' + 5HR 2 _ 5w + 16//A 3 _ 5m , 

n _ c i 8 -Ro— i 28£ 3 _5„,£ 3N \ 

«l-5„ - 0 - (, ^-g- + g £ , + -ggj-j 

- 9A' + 8 HR„_ im + 28Hft 3 _ 5 „. 
Transposing, 

Ri-5m — (1 + 2H)R 2 _5 m — 5 HR 3 _ 5m — A, 

^i—5m ~ 5H£ 2 -5 »i — (1 + 16//)// 3 _ 5w = 4A, 
^i-5m - 8//A 2 _ 5m - 28/£R 3 _ 5m = 9A. 


Solving, 


^ 1 —5m 


A(9 + 42// + ll// 2 ) 


i2»_ s 


/?, 


1-18// + 3// 2 
A(8 + 19/4) 


1-18 H + 3// 2 


A(5 - 6 H) 


3_5m 1 - 18// + 3// 2 

But P 5m = /?i_ 5m + 2£ 2 _5m + 2 R 3 _ 3m , 

ia p _ A(35 + 68//+ ll// 2 ) 
le ’’ 5 "' 1 - 18// + 3Z/ 2 

This last value may be readily checked. In the seven- 
raft case with load reduced until /? 4 _ 7 = 0, giving 
the five-raft-maximum case, by setting A 4 _ 7 equal to 
zero in the case of seven rafts acting, not maximum, 
the above value is obtained. 


Five Rafts Acting, Not Maximum 

The first two equations are the same as for the fivc- 
raft-maximum case. The third equation is as given 
below: 

/?i_ 5 - (1 + 2 H)R,_ :> - 5HR 3 _ 5 = A, 

Ai_5 - 5 HR S _ S - (1 + 16//)/? 3 _5 = 4A, 

R\ — 5 + 2 R.,_ s + 2R 3 _ 5 = P. 

When solved, these yield 

£( 1 + 18// + 7// 2 ) + A(10 - 2H) 


Ri-o 


/T = 


5 + 34// + 7// 2 
_ £(1 + 11//) + A(5 + 4 H) 


5 + 34// + 1H- 


R £( 1 - 3//) - A(10 + 3 H) 

3-5 5 + 34 H + 1H~ 

Three Rafts Acting, Maximum 

In the manner previously used, the following two 
equations are obtained: 


= C('+ + -**-*•>-* 


') 




9 6 El 

= A + 2 HR,_ 3m , 

_ (AaL 5R,_ 3m L*\ 

* m -”- C \-T + ~ 6£7 ) 

= 4 A + 5 HR.,_ 3m . 


Transposing, 

*i-s» - (I + 2 H)R.,_ 3m = A, 
*i-8» - 5 //A 2 _ 3w = 4A. 


Solving, 


. _ A(4 + 3 H) 

I —3m 1 - M ’ 


R — ^ 

R2-S,„ - , _ 


But P 3m — R i_ 3m + 2 /£>_ 3m , 

thati.,P to -*Q2 + M. 

3m Y 

This value may be readily checked by setting 
R :i _ r> = 0. 




























REACTIONS OF ARTICULATED PONTON BRIDLES 


207 


1 hree Rafts Acting, Not Maximum 

For this case, the hist equation is the same as the 
hrst equation in the three-raft-maximum case. The 
second equation is 

Ri- 3-(l + 2H)R.,_ 3 = A, 

R-l —3 + 2«o_g = P. 


Solved, these give 


Ri- 


3 


F(1 + 2 H) + 2 A' 
3 + 2 H 


R 


P - K 
3 + 2 H 


This last value when set equal to zero checks the 
value given for R lm above. 



Figure 15. Eight rafts acting, maximum. 































































208 


PONTON BRIDGE REACTIONS 


Eight Rafts Acting, Maximum 

Figure 15 shows this case, with the various values 
having the same significance as in Figure 14. The 
displacements due to articulation and deflection are 
above the point of application of the load. The fol¬ 
lowing equations may be written 


77 1_ 8m 


77o —8 m 


(t qL 3 R^L* 
\2 2 '4 6 El 


23 7? L ,_ 8m £ 3 47 7?,_ S ,„L 3 71 7? 4 _ 8 ,„£ 3 \ 

4 6 El 4 6 El 4 6 El ) 


Transposing, 

(l -|h)Ri_ 8 .+ (-1 -^h)r 2 _8„. 

+ ( ^ + ( j^ )^ 4 - ~ 

(l ~ — gtn + (- 

+ (-1 - + (- = 6K 


= 2K + ?//«,_*„ + ^HR 2 _ 8m 

+ ^HR,_ 8m + n 


(l -5 h)Ri-8» + (- ”h)« 2 - 8 ,, 

+ (- ^h)«=-8„ + (-1 - = 12A' 


/? /? - r 4. u 

1 — 8m — ^3-81)1 — G I — -y T J 


6 £7 


■ 50 7? 2 _ 8m L 3 118 7?s_ 8m L 3 190 7? 4 _ 8 ,„£ 3 

4 6£7 4 6EI + 4 6£7 


-aa: + |h/{ 1 _ 8 „ + 


, ii8„,. 190 „„ 

4—y m 4—y 77/? 4 _ 8m , 


R _ u _ r (24aL 9 R,_ Sm V 

n i-9m /t 4-8ni ^^2 2^4 6£/ 

77 7? L ._ 8 ,„£ 3 193 7? a _ 8 ,„£ 3 333 7? 4 . 8m 7A \ 

4 6£7 " r 4 6£/ ^ 4 6£7 y 

= 12*:+ + ^HR a _». 

, 193 „ R 333 „„ 

4-y nK s _ 8m H-y MK 4 _ Sm , 


r /40«L 12 7? 1 _ 8 w L 3 

/?1 - 8_0 " C (,T'2' + T~6£7 _ 

104 7? 2 _ 8m L 3 ^ 268 7?.,_ 8m L 3 , 480 7? 4 _ 8m £ 3 


+ 


6 £7 


+ 


6 £7 


+ 


4 — 

6£7 ) 


l 9 104 

= 20 K + ^777? a _ 8w + ™HR 2 _ 8m 

, 268 „„ , 480 „„ 

4-y 7l7l-}_ 8m H-y fl/t4-8m* 


(l -^h)r,_ s „, + (- ^h)r 2 _ 5 ,„ 

+ (- ^h)k.-s» + (- - 2oa 


.Solved, these yield 


77 1—swi — 


77._«,„ = 


A^20 + 47677 + 67077 2 + ^ 77 3 ^ 

] _ ^0// + 1|^77 2 - ^77 3 + |t7 4 
4 4 4 4 

A^18 -f 24677 + - y77 3 ^ 

1 _ 39077 + i|^77 2 - ^77 3 + |t7 4 

4 4 4 4 


77 s _s m — 


< 


378 ; 


15; 


A( 14 + 1377 - T^// 2 + 4f77 3 


L3 “ 8 ” ,_ 390 H + 483 H2 _81 H 3 + 3 H ; 

4 4 4 4 


77 4 _ 8 m ~ 


A ^8 - 8777 + 3077 2 -|t7 3 ^ 

1 _ ^77 + i|^77 2 - ^77 3 + |-77 4 
4 4 4 4 


But 


TV - 27?, _ Sm + 27?2-s>» + 27? 3 _ Sw + 27? 4 _ S)n . 
Substituting the values found above, 

A (120 + 129677 + 130877 2 + 224 77 3 ) 


= 


^77 4- ^77 2 - ^77 3 + |-77 4 
4 4 4 4 





























REACTIONS OF ARTICULATED PONTON BRIDGES 


209 


Eight Rafts, Not Maximum 

The first three equations are the same as those of 
the preceding case. These, together with the necessary 
fourth equation, are 

+ (~T )«a-» +(-T H ) R< -“ _ 2 K ’ 

(i- 

+ (-1 - 7 ± V ) R 3 _ 8 + (- 75 ? H ) fl 4 _ 8 -6 K , 

(i-|h)r 1 _, + (-^h)b 2 _, 

+ (_2|?h)r._ 8 + (-i -•!+//)«,-„- 12 k , 

2 Iti _g + 2 « 2 _ 8 + 2 R u _s + 2 « 4 _ 8 - R 


Six Rafts Acting, Maximum 
In this case, 

'U-am «2-6*» “ ^9 T + 4 " 6E7 


23 /?,_«, n L 3 , 47 77 H _ 6m L 3 


+ —— - + 

4 6E7 

, , 3„ n . 23,, „ , 47 


t7 77 3 _ 6m L 3 \ 
4 6E7 / 


= 2 A + ^74 771_6m + ^74 R 2 -6m + -^7/ 77 3 _e„ 1 , 


„ _ r /\2aL 6 77, _ Cm £ 3 

«, -c„ - - Myy + J - 6 El 


50, 118 R,_c„„L : ' 


+ _ - + 

4 674 4 674 

r , , 6,,„ , 50,, „ , 118 ; 


— 6A + -77/7,_ 6m + —74 R 2 -om -)—-p7477 3 _ 6m , 


,, n _ r ./24 oL , 9 77,_ r>w L 3 

qyy + r'-to ' 


Solving, 


77 7? 2 _(j m L 3 t 193 7{ 3 _ 6 w L 3 


4 674 ' 4 6E7 


77 is — 


.( 1 + 474 H+ lM5 Ha + Ml^ 


+ -h 1 +7™ ■ + 

r » , 9,,„ , 77,,„ , 193, 


i/ y 


D 


+ 


A (40 - 4874 + 4 74-) 
77 


77o_ 8 — 


P^l + ^// + 1^74- - 18 74 3 ) 


77 


+ 


A (24 + 96 74 - 20 74-) 
77 


- 12 A + -jHR l _ Gm + —77/7 2 _ (im + —^—7477 3 


1 hat is, 

(i - +)«,-„» + (-1 - f 

+ (- 


I — Cm 


= 2 A. 


773 _ s — 


7^1 + 11^77 - ^44 2 + ^74 3 ^ 


D 


A (8 - 160 74 - 7 6 74 2 ) 


77 


* 4-8 


E^l _ + ^44 2 - ^77 :! ) 


77 


(l - |74^7 ? 1 _ 6w + (- ^74^77 2 _6m 

+ (-! --^74)77 3 _ c „ ( = 

(l -®/f)i?i_em + (-^//)«2_6 I1 . 

- (- ^*0*8 


6 A. 


Km = 12 A. 


A (56 + 208 74 + 60 74 2 ) 

~~D~ 


Solvine, 


77 1 — dm 


A (12 + 95 74 + 36 74 2 ) 

1 57 3 ’ 

| _ 1™h + +-74 2 - ^74 2 
4 4 4 


where 77 = 8 + 38 874 + 66 074 2 + 14274 3 . 





























210 


PONTON BRIDGE REACTIONS 


R 


k(\0 + 27 H - ip/ 2 ) 

2—6m = f+Q Kn 9 ’ 

1 _ H2f/ + —H 2 - -H 3 

4 4 4 


R 


A'^6 - 18 H + if/ 2 ) 

3 -Cm = Too Kn 9 

1 _ + -rH 2 - 2-H 3 

4 4 4 


But P Gm - 2 R\ — 6m + 2 A 2 _6m + 2 A 3 _ 


6m - 


= 


K (56 + 208 f/ + 60 H 2 ) 
188 57 8 

1 _ }™h + 2df/ 2 - -m 
4 4 4 


Four Rafts Acting, Maximum 
Here 


(iqL S R 4 _ 4m L 3 23 R 2 . 4m L 3 \ 
\2 2 4 6£f 4 6£/ ) 


= 2A + ^HRi 


23 

-4m + 


■4m> 


A 


1 — 4m 


0 


/12qL 6 R\- 4m L 3 50 A 2 _ 4w L 3 \ 
V 2 2 4 6£f 4 6£f ) 


It will be noticed that this same value is obtained 
when jR 4 _ 8 is set equal to zero. 

Six Rafts Acting, Not Maximum 

Two of the equations for this case are the same as 
two for the six-raft-maximum case. These, together 
with the third equation, are 

+ (-^h)r 3 _ 0 - 2K, 

(> -|H)r.-« + (-“h)k 2 _ 6 

+ (-1 - 6 K , 

2«,_ ii + 2li._ 0 + 2;( 1 _ t = />. 


= 6 K + 


Transposing, 

(l - + (-1 - f - 2K, 

(l - + (- ™+)fi,_ 4m - 6 K. 

Solving, 

K l " 4 " 1 99 9 * 

1 _ ££f/ + -H 2 
4 4 

„ _ 


When solved, these equations give the values 


From the equation 


p(i + + ii-f/ 2 ) + K (16 — 4/7) 

6 + 88 H + 38 H 2 

P(l + 17 H - if/ 2 ) + K (4 + 20 H) 

6 + 88 H + 38 H 2 

p( 1 - ~H + |f/ 2 ) - K (20 + 16 H) 
6 + 88 H + 38 f/ 2 


P 4m = 2R 1 _ 4m + 2R 2 _ 


4m > 


there is obtained 


P 


4m 


K (20 + 16 H) 

1 _ ii h + if/ 2 

4 4 


the same value which comes from setting A 3 _ 6 equal 
to zero. 



















REACTIONS OF ARTICULATED PONTON BRIDGES 


211 


Four Rafts Acting, Not Maximum 
The necessary equations for this case are 

(l - + (-1 - y)«^4 = 2 K, 

2 ft,_, + 2K,._4 = P. 


example, the investigation is being conducted on an 
odd number of rafts and the load being considered 
lies between P 5m and P- m , then the applicable case is 
Seven Rafts Acting, Not Maximum, and the equa¬ 
tions for this case will give the values of the reactions 
and permit determination of the shear and moment 
curves. 


These give the values 


Ki 


— 4 


7 * 2-4 


p(l + + 4A 

A + 10 H 

P (}-l H )-A K 

4 + 10H 


Two Rafts Acting, Maximum 
For this case the equation is 


n _ | 3 R i 

Kl - 2m - 0 ” T + 4 ” 6 El ~) 


= 2 A' + yHRi. 
A 


IL2 - 2 Loads Different From a Single 
Concentrated Load 

Each of the foregoing derivations has been made 
for a single concentrated load placed at the middle 
of the structure. Provided an actual tank, truck, or 
other load is not spread over too great a length, fair 
accuracy will be obtained by assuming that the reac¬ 
tions will be the same as for a single concentrated load 
of the same magnitude. The actual distribution of 
loads, however, will be used in drawing shear and 
moment curves. It is felt that the error due to this 
assumption will be no greater than those errors aris¬ 
ing from variations in articulation due to shop inac¬ 
curacies and to disregard of the facts that the pontons 
do not have the shape of a box, and that submergence 
and reaction are not directly proportional. 


This gives the value 


Identity of Methods 


R 


1—2m 


2 A' 



from which is obtained 



Two Rafts Acting, Not Maximum 


The methods used with articulated bridges may be 
applied to continuous, unarticulatecl structures if K 
is set equal to zero. Thus, for continuous structures, 
the methods summarized at the end of this section 
and those at the end of the section on continuous 
structures should give identical results. This may be 
illustrated by an investigation of the five-ponton 
structure of Figure 16. Two equations may be written 
(for / = 1, and / = 2), since by symmetry there are 
only two unknown interior ponton reactions. 


In this case 



1, 21 Use of Equations 

When the make-up of the structure has been deter¬ 
mined, values can be computed for A and H, and the 
values of P lm , P 2m , P Sm , etc., can be computed. If, for 


4L 



2L 

p 





\ / 

7 


S, 





\ r 


n i 



_ 

i i 


i i 




R, 

R, 

R„ 

R„ 



Figure 1(3. Continuous five-ponton structure and load. 














































PONTON BRIDGE REACTIONS 


212 


For / = 1, 


Therefore, dividing all terms by 2 , 


*,(4-, — I+ L^i) 

+*< 4 - 2 —> + ^ J ) 

+ - 3 - 1 + Llill) 

+ /?,//(2 • 1 • 9 ) + 4 /?, 


7 

1+117/ 

1 + 

1177 


1 + 1677 

3 + 

1677| 


4 + 167/ 

1 + 

117/ 


2 + 22 H 

3 + 

167/| 


7(3 + 497/ + 176/7 2 - 1 - 277/ - 1767/ 2 ) 
“ 12 + 112/7 + 2567/-' - 2 - 447/ - 24277- 

7(2 + 22/7) 7(1+11/7) 

~ 10 + 68 H + 14 H- 5 + 34 H + 1H- 


+ /?,,// [1 • 2(2 • 4 • 2 - 4 - 1 )] 
+ R 3 H [1 • 1 (2 • 4 • 3 - 9 - 1)] 


- p[4 - 2 - 


1 + 


2 . j • 2' 


+ PH [2 • 1 (2 • 4 • 2 - 4 


|4 + 16/7 1 + 117/j 

\2 + 22 H 1 + 16 H\ 

2 “ 10 + 68 H + 14/7 2 

P (4 + 80 H + 25677-' - 2 - 44 H - 242 H-) 
10 + 68 77 + 1477- 

P( 2 + 36/7 + 14/4-') 7(1 + 1877 + 77/ 2 ) 

1)]. 10 + 687/ + 1477- “ 5 + 347/ + 77/ 2 


Since 7/3 = /?,, this may be rewritten 


T he value of /?,, ( = /? 5 ) may be obtained from the 
equation 27 = 0. That is, 


87?! + 327//?! + 2/?o + 227/7?., = 27 + 227/7. 


«i 


Similarly, for / = 2, 

2 . 2 • 1 


[«- 


1-2 + 


4 


Or 


, , 9 . 9 . 9 ' 

+ /?« 4 - 2 - 2 + —- : - 


* 


r 9 . 9 . ‘t~l 

+ 7? 3 [4 - 3 - 2 + 


+ 7,77 [1 • 2(2 • 4 • 2 - 1 - 4)] 
+ 7?.,77 [2 • 4 • 4] + 47?,, 

+ 7? ; ,/7 [2 • 1 (2 • 4 • 3 - 9 - 4)] 

r 9 . 9 . 9-1 

-p[4-2-2 + +4-?] 


+ PH [2 -4-4]. 


47 j + 44777, + 6 R, + 327/7,, = 27 + 32777. 


27 0 + 2/?! + R, - P = 0, 

7?o = i/ 2 (P - 27, - 7?o‘). 

w r D 27(1 + 11H) + 7(1 + 18 H + 77/ 2 )1 

/2 L 5 + 347/ + 77/ 2 J 

# 

7 5 + 347/ + 777 2 - 2 - 2277 - 1 - 187/ - 77/ 2 
= 2 5 + 34 H + 777 2 

7 2 - 67/ _ 7(1 - 37/) 

= 2 5 + 347/ + 77/-' 5 + 347/ + 77/ 2 ‘ 


File following comparison is found between the 
notations of the summaries for the unarticulated and 
the articulated bridge reactions: 


U narticulatecl 


R 1—3 

R 2 - 5 

^ 3-5 


Articulated 

R, 

Ri 


The values computed are the same for the case in 
which 7 = 0. 14ie methods of analyzing articulated 
bridges, however, will give increased speed for cases 
of symmetrical loading in continuous, unarticulated 
bridges provided that the actual load does not have 
too great a distribution. 































i 




**=9 




*1-1 

P<Pu 


* 1-1 = p 


1 m 


TTT 

*2—lm ~ 0 *1 -1m *2-lm = 

*,m « K 




r-^F=i 


Ef3^My-^-H=Y L -~- 1 

*2-3 *I —3 *2—3 

p 3m > p> Pirn 


3m 


TTTTT^ 

*3-3Ml = 0 *2—Sm Pi-3m *2-3 m *3 —3m ~ 0 


A(10 + 3 H) 
- 1 " " T~3/T" 




— f—T- 


^TT^yTT^ 

*3—5 *2—.'. *1 —5 ^2—5 *3 

*5- > * > P3m 


5m 


TTTTTTT' 

*4 —5m ® 0 P\—Z> m *2 — 3* *1—.'.m P-2 —3m *3—5m *4—5m ~ ® 

p A(35 + 68// + II// 2 ) 

3 " “ 1 — 18// -h 3 H- 






rrrr^rfT" 

*4-7 * 3-7 * 2-7 *,_ 7 * S - 7 * 3-7 Pa -1 

P 7m >P> P; m 


*1 —lm ~ A 


D _ P(1 + 2 H) + 2A 
* 1-3 3 + 2 H 


R. 


P - A 
3 + 2 H 


Reactions of Ponton Bridges 

(with articulations) 


METHOD OF USE 
For a selected structure (that is, with 
H and A known) determine, by means 
of these formulas, the values of P\,„,P> m , 
• • • ■ P$w Consider the actual load as a 
center concentrated load. Place either 
at a joint (even number of rafts) or at 
the center of a raft (odd number of 
rafts). If odd, determine where the load 


Notation 


H 


and A = 


comes with relation to P lm , P am , P Sm , 
P 7m* If (say) between P im and P Ttm , the 
reactions are given as/2,_ s ,i? 2 _ 5 ,/J 3 _ 0 . 
Compute the reactions, replace the as¬ 
sumed concentrated load by the actual 
load, and draw the shear and moment 
curves for the structure. 


CM 


6 El 

CaL 

2 


where E = Modulus of elasticity of balk. 

I = Moment of inertia of balk. 
a = Angle of articulation (radians) between rafts. 
L — Length of one raft. 

C = Raft displacement per unit of depth. 


_ A'(4 + 3//) 
1 “ 3m 1-3/f 


A,_ 


3 A 


2-3m j _ m 


„ _ P(\ + 18// + 7 H-) + A'(10 - 2 H) 

K '- 3 5 + 34// + 7 //* 

_ P( 1 + 11//) + K(5 + 4H) 

K *~ a -5 + 34// + 7H- 

_ P(1 — 3//) — A(10 + 

R*- 3 -5 + 34/T+ 7 //* 


*, 


A(9 -f 42//+ ll//2^ 

-T^wr+w* 

A (8 + 19 H) 

T^wr+jm 

A (5 - 6 H) 


R.-r» 

R *- am “T^18H+17^ 


7m 



P(\ + 72// + 131//-JJ- W) + A(28 - 26 H + 2// 2 ) 
Ri-i “ -- 7^fT96H 4- htt/f* + 26//» 

P( 1 + 57 H + 46/T0jt-A_(21 + 16// _ 4/72) 

* 2-7 - — 1 -rn9677TT9377^T^ 

p /1 + 23H - 1 8// g ) +_A(65 H + 1 4//*) 

P 3-1 -- 7 + l9677^TT93^ r +^677 ;r 

P/I - 18// + 4- 1 1//*) 

p 4 -i - —— 


A(16 + 252 H + 256Hi+ r jJ"3 

R _ A(12 + 29// - 30//*) 

*i-7». 1 _ 60//+ 42//* iH 

1 7M 1 - 60// + 42//* - 3 H A 

K (15+ 10fi« + 73W 

R _ A (7 — 42// + 6//*) 

*2-7m “ , _ (]{)H + 42 H 1 - W 

1 - 60// + 42//* - 3 H* 


^"-1-r- 






* 1-2 *i-j 

P < Plm 


P-2, 


2 m 


P'2 — ‘2m = 0 Rl-’l R\-‘l R-l—2m ~ 9 

4A 


Plm = 


1 - 

4 


t= 4=--+-- 




•^2-4 -^1 —4 P\-4 P’2 -4 

P 41 H > P > Plm 


4m 



1- r- 


^ ~ ~r~ ~—r 


: ^ ; : 

*3-0 *2-0 *1-0 *1-0 *2—6 *3-0 

*0m > * > *4m 



6 m 



P'2 — 8 *1-8 *1-8 P'2-3 

P*m>P> P0 m 


*4—1 



8 m 


*1- 


*1 —2m = 


2A' 


1 - jH 
4 


*i-4 


(l+f//) 


+ 4A 


4 + 10H 


p (l -%h) - 4A' 
* 2 _ 4 = -> 4 4 ,/ fi _ 


4 + 10// 


*1 —4i 


*2 — 4n» 


K ( 6 + f") 

1 - ^// + |//2 

4 4 

1 - + ^//* 

4 4 


*1 -u 


p(l + B±// + ^//-') + A'(16 - 4 H) 


6 + 88 H + 38//-' 

*3-n 


*.. 


p(l + 17// - |//*) + A'(4 + 20 H) 


6 + 88 H + 38//- 


/> ( I ~ ~ *(20 + 16//) 
6 + 88 H + 38 H- 


R A'(I2 + 95//+ 36//-') 


A 10 + 27 H 


I — tt// + =¥■//=* - 2//a 

- 4 4 


*3- 




«■) 


A (6 - 18// + ?//*) 

1 - ^// + ^lH- - |//' 


1 - ^//+ ^lH- -%H* 

^44 


p(j + i^H + l^//s + //*) + A (40 - 48// + 4//2) 

“ 8 + 388 H + 660 H* + 142// 8 

P^l + + 1^//-' - 181/*) + A'(24 + 96// - 20//*) 

*-•-« “ 8 + 388 H + 660//* + 142//* *«-i 


p(l + _ 23[ H2 + N*//*) - A'(8 - 160// - 76//*) 

8 + 388// + 660H 2 + 142H* 


p(l _ + 52// 2 - |//a) _ A(56 + 208// + 


60//*) 


8 + 388// + 660//* + 142// 3 


*, 


*2 


A (20 + 476 H + 670 H- + ^// 3 ) 
1 _ ^9 H + i83 W2 _ 81 HH + 3 h< 




a: ( 18 + 246H + 15i«s _ ”«:.) 


1 _ m, + m H * 

4 4 


+ ?//* 


*4 


AC (l4 + 1SH - 

_ 590 H + 4_|8 H2 _8, H: r^ 
Av (8 - 87H + 30/4 2 - |«») 


,_3|) H + 4 8S^_«L HS + s H1 
















































































































































































































































































































Chapter 1 2 

BRIDGE, PONTON, AND FERRY DESIGNS 


Summary 

esigns for a variety of structures intended for 
military use—bridges, pontons, and ferries—were 
prepared at the request of the Engineer Board of the 
U. S. Army Corps of Engineers. 

Among the structures designed are a 20-ton articu¬ 
lated bridge, a portable ponton bridge and ferry for 
30-ton tanks, a structure which can be used as a pon¬ 
ton bridge or as a trestle or overpass for 60-ton tanks, 
a bridge constructed largely of steel pipe, a 200-foot 
portable bridge to carry a 30-ton tank, temporary 
highway trestles, a ponton ferry to support a 90-ton 
tank, tank-ferrying barges, and an amphibious paddle- 
wheel towboat. Other bridges already being used or 
contemplated by the Army were also studied, and in 
some cases these were redesigned for additional appli¬ 
cations. Similar designs were made for ramps for some 
of these bridges. 

In order to provide facilities for landing tanks, a 
landing pier was designed to handle a 30-ton tank at 
sites where tides up to 20 feet may exist. 

With the expected need for repairing or replacing 
enemy-damaged quays in occupied territory, a series 
of alternate designs was developed for foundations 
and floor systems. 

12.1 ARTICULATED BRIDGE FOR 
20-TON LOADS 

To meet the need for an articulated bridge on 
rubber floats to carry division loads up to 20 tons, 
designs were prepared for a structure to make use of 
wooden floor chess and rubber floats already stocked 
by the Army. a 

The design shown in Figure 1 contemplates the use 
of five parallel, welded-steel balk as main carrying 
members, each approximately 5y 4 inches wide, 16 
inches deep, 15 feet long, and weighing 380 pounds. 
The details are so arranged that the balk are alike 
end for end and top for bottom and cannot be as¬ 
sembled in a wrong position. 

a This investigation was conducted by the Drexel Institute of 
Technology, Philadelphia, l*a., under OSRD contract OF.Msr- 
41, and by Carson & Carson, Philadelphia, Pa., under contract 
NDCrc-41 and OSRD contract OEMsr-216. 


Because the loads to be carried and their positions 
on the roadway are not definite, and because the 
chess to be used are rather thin, there is uncertainty 
regarding the division of loads among the five balk 
in any span. As far as moment is concerned, this is 
not so serious, since four balk have sufficient strength 
to carry the moments if these are equally divided. In 
the case of shear, however, particularly in the simple 
spans at the ends of a structure, this may cause 






cfce aanJEN BML 


213 








































































214 


BRIDGE, PONTON, AND FERRY DESIGNS 


trouble and a slight increase might be required in 
the size of one or two diagonals at each end of each 
balk. 18 

<22 30-TON TANK PONTON BRIDGE 
AND FERRY 

Designs have been prepared for a portable ponton 
bridge and ferry, each suitable for carrying loads up 
to and including 30-ton tanks. The equipment has 
been planned to give maximum ruggeclness, simpli¬ 
city, interchangeability, and mobility to meet mili¬ 
tary field requirements. 11 

I he general structure of the ponton bridge set up 
hir a 210-foot crossing is indicated in Figure 2. It con¬ 
sists of ramp sections supported on special spread 
bearing shoes at their shore ends and double pontons 
at their river ends for both ends of the bridge. Be¬ 
tween the double pontons is a series of spans sup¬ 
ported on single pontons. 1 he bridge deck consists 
of all-welded panels. The pontons, also all-welded, 
have rectangular sections throughout, and each is 

bThis investigation was conducted by the American Bridge 
Company, Pittsburgh, Pa. 


divided into four watertight compartments, stiffened 
with lattice frames, and equipped with manholes to 
permit ready access to the interior. 

All the units for this 210-foot bridge would weigh 
161,200 pounds or 765 pounds per linear foot of 
bridge, and could be transported together with a 
crane and necessary personnel on ten 12-ton articu¬ 
lated trailer trucks. 

By adding auxiliary molded ends, two bridge pon¬ 
tons (Figure 3) and one section of bridge deck can be 
combined to give a ferry 20x38x3 feet deep (Figure 4). 
Fully loaded, this ferry has a displacement of 2814 
inches, leaving a freeboard height of 7y 2 inches. The 
ferry itself has a weight of 38,200 pounds. 

The transportation requirements would lit in very 
well with the requirements of the ponton bridge, for 
two additional trucks would provide transportation 
for the formed ends of two ferries and for loading 
aprons required for two banks. To provide a com¬ 
plete ferrying unit composed of two ferries and two 
loading aprons, together with a truck crane, hand 
tools, and necessary personnel, seven 12-ton trailer 
trucks would be needed. 


</> 

CD 

cn 




Figure 2. Assembly ot 30-ton bridge. 





































































































60 TON TANK TRESTLE AND PONTON BRIDGE 


215 



Figure 3. Ponton for 30-ton tank bridge. 


It is believed that expansion of the basic principles 
developed in this study would lead to satisfactory 
designs for ponton bridges and ferries to accommo¬ 
date 50-ton tanks. 5 

12 3 60-TON TANK TRESTLE AND 

PONTON BRIDGE 

Designs have been made for a trestle structure that 
can support a 60-ton tank and can serve, with some 
modifications, as parts of a ponton bridge. 11 



s - 

II 

-!■ — 

; lj njT 

i 1 h 'i 

I 1 !' 'i 


o 

CM 

f 2 

* 

'L. 

O , 

_z 

h 

UJ 
• =CD 

= o 

Oi 

—? -h -r 

1 

£i '! 'i 

gf * h 

d !L 


--r - -r- 

ii H 'i 

ii ii i| 

!U_U_Ii 






MULUC.U cnu 

\ 


*r< >w 

\ 

/ 

/ 

4-0" 

4- STANDARD PONTON 

--30'-0"-*• 

4-0" 


38'-0"- 


Figure 4. Ponton modified with molded ends to serve as 

30-ton tank ferry. 

As a trestle (Figure 5), the proposed structure con¬ 
sists of bents (two columns and a transom) spaced 
about 23 feet apart. By splicing the columns, the 
floor may be placed about 40 feet above the bottom 
of the column grillage. The bents support longi¬ 
tudinal, welded, open-webbed balk that carry the 
floor beams and an open-grid floor. Six balk are 
required in each span to support a 60-ton tank, four 
lo carry a 30-ton tank. The same structure may be 
used as an overpass (Figure 6) and presumably as a 
dock or as a trestle for light railroad loads. 

The same grid floor, floor beams, and balk will 
serve as a ponton bridge, with the balk resting on 
25-ton pontons (Figure 7). Special connections are 
planned to reduce the bending moment in the balk 
and to take advantage of the ponton flotation under 
and near the load. For use as a bridge, the structure 
would be assembled into 25-foot rafts, with three 
pontons per raft for 60-ton tanks and two for 30-ton 
loads. 11 

Reliance for longitudinal stability is placed in 



girnm 































































































































BRIDGE, PONTON, AND FERRY DESIGNS 


2 If) 


CLEAR ROADWAY- 


12- 7“ 




part on a detail involving the use of set screws. 
Laboratory tests showed that such screws have suf¬ 
ficient holding power to take a load of 5,600 pounds 
without slipping. 11 


Since the attention of the Engineer Board was 
taken by other bridges, studies were not continued 
beyond the preliminary design stage. 12 


TUBE BRIDGE 


THE INGLIS BRIDGE 


A bridge design taking advantage of the load-re¬ 
sisting properties of steel tubes has been prepared 
for truck, tank, and railroad loads." For tanks, if only 
one were allowed on the bridge at a time, the struc¬ 
ture would permit a 60-ton load on a 150-foot span, 
a 30-ton load on a 180-foot span, and a 20-ton load 
on a 210-foot span. Considering its capacity, the 
bridge is relatively light in weight, its heaviest stand¬ 
ard member weighing about 1,850 pounds, and all its 
members may be readily nested and transported. 

The features of the design are shown in Figure 8. 
For use as a highway bridge, steel guardrails are fur¬ 
nished and the space between top chords is filled in 
with an open-grid steel floor which will be Hush top 
with the chord. Four floor sections, each weighing 
about 220 pounds, are used to fill in the 5-foot panel 
between two floor beams. The structure may be used 
as a railway bridge if the guardrail and open-grid 
floor are replaced with 8x8-inch ties, 12 feet 6 inches 
long, placed 14 inches center to center on the top 
chords. 


The Inglis bridge, 0 with trusses composed of pin- 
connected tubular members, was examined, and a 
study made of its capacity based upon conservative 
allowable unit stresses and its use as a double-story 
bridge.' 1 

The greatest element of weakness in the structure 
appears to be in the lack of top-chord bracing in the 
single-story bridge. As built, there seems to be no 
justification for the assumption that the unsup¬ 
ported length of the top-chord members is one panel 
length or 12 feet. The loadings given in the design of 
the bridge have a factor of safety of 1.07 and cannot 
be regarded as allowable for prolonged service. For 
all cases except the single-story, single-tube one, the 
structure will be materially weakened and probably 
unsafe unless all of the compression collars are 
screwed out to their full travel. 2 

0 A portable bridge designed by Professor C. E. Inglis, built 
by the Royal Engineers. 

<1 This investigation was conducted by the Drexel Institute of 
Technology, Philadelphia, Pa., under OSRD contract OEMsr-41. 



Figure 7. Assembly of 60-ton tank ponton bridge. 




















































BETHLEHEM STEEL COMPANY PORTABLE BRIDGES 


217 



SECTION Z 


Figure. 8. Details of tube bridge construction. 


126 200-FOOT PORTABLE BRIDGE 

A 200-foot portable bridge to carry the medium 
tank, with a weight of about 27i/2 to 30 tons, has 
been designed with open-type floor, floor beams, 
chords, end posts, and main gusset plates to be made 
of alloy steel, and the other web members to be made 
of ordinary bridge steel. a 

The construction is illustrated in Figure 9. In 
order to settle the relative erection advantages of pin 
connections and bolts, alternate designs were pre¬ 
pared, one showing bolted and the other pin-con¬ 
nected construction. Once it has been determined 
which type is preferable, a light traveller may be 
designed to run on the curb channels of the floor 
and to serve for the erection of the structure. 

The plans as shown here have been made with 
the presumption of using cantilever erection. In the 
case of either cantilever or swing erection, the size of 
the chord members would be determined by the 
erection stresses. It is believed that if this design be 
completed, temporary strengthening of a few of the 
chord members at the center of the structure for 
these erection stresses would permit extending the 
bridge for spans up to 260 or 280 feet. 1 


127 BETHLEHEM STEEL COMPANY 
PORTABLE BRIDGES 

Designs for two portable bridges of 200-foot maxi¬ 
mum clear span were examined to determine their 
general suitability and safety.' 1 Each bridge as 
planned by the Bethlehem Steel Company would 
be erected as a cantilever from similar parts that 
serve as an anchor arm counterweighted for erection. 
In each case it was intended to use the anchor arm 
and the cantilever, when completed, as a continuous 
span. 

The first of these, Bethlehem Scheme E, is a design 
for a bridge made up of box sections 28 feet long, 
5 feet wide, and 11 feet deep. The intermediate sec¬ 
tions weigh 12,300 pounds each. Two trusses com¬ 
posed of these box sections are spaced 9 feet center 
to center and carry on their upper chords a roadway 
of 18 feet clear width. An erection method is pro¬ 
posed to allow the placing of a 102-foot anchor arm 
and a 200-foot cantilever arm complete with floor in 
50 minutes. The bridge was designed to support a 
20-ton truck with a 16-ton trailer in each of its two 
lanes. It contemplates the use of an alloy steel with a 
basic stress in tension of 35,000 psi. 

























































































































218 


BRIDGE, PONTON, AND FERRY DESIGNS 


Similar box sections are planned for Bethlehem 
Scheme F, but in this plan floor sections are perma¬ 
nently attached to floor beams at the top-chord level 
so that the longitudinal members of the floor will 
assist the chords in carrying compression. Since only 
one lane of tanks or heavy trucks may be supported, 
the total weight of the structure will be considerably 
less than that of Scheme E. 

It was determined that both schemes are, or can 


readily be made, satisfactory from a design stand¬ 
point, and once in place will safely carry their loads. 9 

128 SOLID-FLOOR TREADWAY BRIDGE 

Several years ago, the U. S. Army developed a 
bridge that utilized treadways on rubber floats. As 
main members, the superstructure has four 15-inch 
channels, connected to furnish the two treadways as 




-CRIMP BARS 


TYPICAL SECTION 


5'-0" C. TO C. FLOOR BEAMS 
TYPICAL SECTION 


5 .SECTIONS OF FLOOR IN l2‘-0“ 

, V / , 


6 SECTIONS OF FLOOR IN l2'-0" 
S' 


iMNMit&Mns 


~7*" 7 «r ~*r * >r * 

Li Vj JmT ±*. i m . j.uj la i aa a «_LA 




THROUGH SPAN 



DECK SPAN 


Figure 9. Design of 200-foot bridge. 










































































































































SOLID-FLOOR TREADWAY BRIDGE 


219 



Figure 10. Cross section of old treadway bridge. 


shown in Figure 10. In order to accommodate loads 
with a width of contact of 120 inches, however, it 
became necessary to redesign the structured 

Immediate analysis showed that if the same gen¬ 
eral arrangement were retained, the new design 
would involve widening the treads but retaining the 
distance between inner channels to permit passage 
of the i4-ton truck. The presence of these inner curbs 
is undesirable, for certain vehicles tend to ride them. 
Furthermore, it is generally appreciated that traffic 
slows up when approaching treads, and that this may 
result in serious congestion particularly under black¬ 
out conditions. Consequently, a new design was pre¬ 
pared as shown in Figure 11, with a solid floor and a 
width of 11 feet 9 inches, in contrast to 9 feet 5 inches 
for the old bridge. 14 

It became necessary later to develop a ramp for 
this new bridge which would permit traffic to enter 
and leave it under considerable change in water 
level, such as would exist on a tidal stream. The 
ramp designed for this purpose is shown in Figure 



D=r 

rr-; 

?=-=<; 

j>=====* 1 . 

?■ ' -■■■■■■<» 


, __ ^ 

r __ ^ _ 



[ 

T T 

" 1 ! 

1 Q 


Id l ^ UVLI• AL L 


ELEVATION 
































































































































220 


BRIDGE, PONTON, AND FERRY DESIGNS 


12. Under controlled traffic conditions—that is, with¬ 
out impact—a three-section ramp 38 feet (i inches 
long will support a 34-ton tank, and a two-section 
ramp 26 feet 6 inches long will hold a 55-ton tank. 20 

*29 RAMP FOR SPARKMAN AND 
STEPHENS BRIDGE 

At the request of the Engineer Board, a design was 
made for a landing ramp to be used with the Army 
bridge devised by Sparkman and Stephens.' 1 The de¬ 
sign, as shown in Figure 13, c alls for complete units 
33 feet long with a clear roadway of 12 feet 5^4 
inches. 21 

i2.io PORTABLE RAILWAY BRIDGE 

In order to determine the possibility of using the 
U. S. Army H-20 portable steel highway bridge as a 
railway bridge, allowable Cooper loads and deflec¬ 
tions were computed for span lengths of 37*/9 to 100 
feet. d Two floor systems were considered, one (A) 
using at the panel points of the trusses a number of 
8x10-inch timbers, 6 feet 3 inches center to center, 
and stringers of the same size over the trusses in order 
to avoid bending stresses in the truss chords, and 
another (B) in which the ties rest directly on the top 
chords of the trusses. 

For plan A, the allowable Cooper load ranges from 
E-34 to E-7 for span lengths of 37*/£ to 100 feet, pro¬ 
viding two trusses are used, and from E-51 to E-ll, 
providing three trusses are used. 

For plan B, the allowable load ranges from E-32 


to E-6 for span lengths of 37*4 to 100 leet with two 
trusses, and from F-48 to F-10 with three trusses. 10 

•2-11 TEMPORARY HIGHWAY TRESTLES 

Three designs for temporary highway trestles have 
been prepared to provide structures which can be 
erected easily and quickly in the field. Wood piles 
and caps are used in one case, steel H-section piles 
and steel channel caps in another, and steel pipe 
piles and steel channel caps in a third. The super¬ 
structure above the caps, including stringers and 
roadway, is the same for all three designs. The general 
features of the plans are illustrated in Figures 14, 15, 
and 16. 

The pipe pile construction appears to lend itself 
more readily to the requirements because of the 
simplicity of field connections. This design provides 
for pipe plug application of the cap assembly and 
pin connection of the stringers to the caps. Bracing 
details arc also simplified, and this type of trestle 
can probably be erected more rapidly than can either 
of the other two. 

A unit similar in construction to the Austin West¬ 
ern “Badger” crane rigged as a pile driver, with or 
without hanging leads, should be able to handle the 
piling. Necessary modifications include the selection 
of a power unit of sufficient capacity to handle the 
crane, and the addition of a 315-cubic-foot air com¬ 
pressor. 

While soil conditions at the site will determine the 
speed, a time schedule of 40 minutes for driving one 
bent and one panel appears reasonable. This is based 

12'- 5^ "clear 

ROADWAY ^ 


SECTION THROUGH RAMP 



Figure 13. Ramp for Sparkman S: Stephens Army treadway bridge showing experimental approach. 
































90-TON TANK PONTON FERRY 


221 


BENT l0'-0" C/C 



on complete preliminary preparation and on assur¬ 
ances that the cap assembly and panel deck and the 
stringer assembly are all available within reach of 
the power-driven unit. 3 


12 12 90-TON TANK PONTON FERRY 

Plans have been made for a heavy ponton ferry, 
capable of carrying a 90-ton tank or equivalent loads 
of fuel, water, personnel, or other military supplies. e 
As shown in Figure 17, the ferry consists of four 
units, each 40 feet long, 10 feet wide, and 4 feet high, 
constructed of electrically welded carbon or alloy 
steel with watertight compartments. Construction of 
one unit is illustrated in Figure 18. 

The units can be carried on trucks, trailers, or 

e This investigation was conducted by T. R. Tarn, Pitts¬ 
burgh, Pa., under OSRD contract OEMsr-138. 


TYPICAL BENT DETAIL 

Figure 14. Design of temporary highway trestle—wood 
pile construction. 


BENT lO'-O" C/C 



BENT IO‘-0" C/C 



BENT DETAIL 


Figure 15. Design of temporary highway trestle—steel Figure 16. Design of temporary highway trestle—steel 

H-pile construction. pipe construction. 


























































































































































































































































































































































222 


BRIDGE, PONTON, AND FERRY DESIGNS 


freight cars, and can be assembled in 20 minutes or 
less. They can be used as separate units, in groups, 
or as a continuous articulated floating ponton bridge. 

A separate, self-contained towboat is recom¬ 
mended as the most desirable means of propulsion, 
although either demountable or permanent propel¬ 
ling equipment can be installed on the units. Designs 
for a suitable towboat and a method of transporting 
it on land are given in Figure 19. 

Equipment to transport and place in service one 
four-unit ferry consists of eight transport trucks and 
four Caterpillar-type tractors. In addition, eight 
transport trucks would be needed to carry the two 
towboats, two tractors for the towboats, and two 
tractors for launching material. 0 

In order to simplify launching and assembling 
operations, plans were made later for movable con¬ 
fined launching cradles that carry a ponton unit on 
steel runners, and in turn are carried on rollers in¬ 
stalled within the side frame portions of the trailer 
chassis. These make it possible to launch the pontons 
directly into the water. Each transport unit—a trac¬ 
tor and its trailer—is therefore completely equipped 
as a self-supporting and self-contained unit to serve 


as a transport and launching medium for one ponton 
unit. 7 

12-13 DUKWS AS PONTONS 

In another section of this volume, a report is pre¬ 
sented on the use of the amphibious DUKW as a 
ponton ferry and its possible use in a ponton bridged 

12 .H TANK-FERRYING BARGES 

In order to ferry tanks and similar loads weighing 
up to 90 tons, small barge units were designed in 
May 1941 as shown in Figure 20. g Each barge would 
be 14 feet 5 inches long and 7 feet (3 inches wide, con¬ 
structed of welded steel, and weighing about 2,500 
pounds. With 16 barges carrying a 90-ton tank, dis¬ 
placement to a 2-foot 5-inch water line in fresh water 
would be about 13,250 pounds, leaving a freeboard 
of 2 feet 7 inches. The barges could be nested for 
transportation. 

f See Chapter 3. 

g This investigation was conducted by Sparkman & Stephens, 
Inc., New York, N. Y., under OSRD contract OEMsr-36. 



Figure 17. Assembly of 90-ton tank ponton ferry. 




































































tank-ferrying barges 


223 


It the barges could be built of plywood skin on a 
steel frame, the weight could probably be reduced to 
about 1,500 pounds. 

Pin connections were designed primarily for ease 
in assembling the units, and to provide for both 
tensile and compression loads in a fore-and-aft direc¬ 


tion. Transverse loads would be handled by sepa¬ 
rately applied steel girders. 

Many of the features of this design later found 
application in the so-called Rhino ferry used by the 
Army, and the nesting feature is used in many Amer¬ 
ican and foreign ponton bridges. 



Figure 18. Plan and side elevation of ponton for 90-ton tank ponton ferry. 


































































































































22-4 


BRIDGE, PONTON, AND FERRY DESIGNS 




Figure 19. Towboat for 90-ton tank ponton fcrrv. 






Figure 20. Plan and side elevation view of nestable tank- 
fern ing barges. 


rhe basic features of the A-frame are shown in 
Fieure 21. This structure would be built of welded 

O 

steel pipe, with each section about 22 feet long and 
weighing less than 2,500 pounds. The members 
would be arranged in the form of a truss, with ad¬ 
ditional cross members to provide extra local sup¬ 
port to the longitudinal members where they are 
carrying a runway. The A-frame would provide a 
means of lifting and suspending a 90-ton tank after 
it had been launched in shallow water. If an I-shaped 
center link were substituted for the section carrying 
the chain hoists, a flat bridge-type structure cotdd be 
made for suspension between barge units to give a 
loading platform. With suitable linkages between 
the ends of such platform sections, these could be 
formed into a ponton bridge. 

Arrangements proposed to meet various ferrying 
and loading conditions are indicated in the diagrams 
in Figure 22. 

Two towing vessels were designed for use with 
these barges, one an amphibious paddle-wheel tow- 



































































































TANK FERRYING BARGES 


225 



Figure 21. A-frame for loading tank-ferrying barges. 















































BRIDGE, PONTON, AND FERRY DESIGNS 


226 






1 

■ 






r 

. ^ V 


✓ 


PLAN VIEW 

E 



PLAN VIEW 

B 


PLAN VIEW 

D 


PLAN VIEW 

F 



Figure 22. Loading arrangements for tank-ferrying barges. 

























































































































































































































































































TANK LANDING SHIP 


227 



boat 11 and the other a tunnel stern towboat. The 
latter, shown in Figure 23, would be constructed of 
phenolic resin plywood on oak frames and powered 
by a Ford V-8 automobile gasoline engine fitted with 
a marine clutch, a reverse gear, a reduction gear, and 
a thrust bearing. An automobile-type radiator would 
provide fresh water cooling. With a screw propeller 
housed in a stern tunnel, this boat would be able to 
work efficiently in shallow water. Its over all length 
would be 15 feet, its beam 6 feet 6 inches, its depth 
3 feet 6 inches, its weight about 2,100 pounds, and 
its speed about 15 knots. 

Although it is believed that a towboat generally 
similar to one of those mentioned above would pro¬ 
vide the most flexible single means of propulsion 
under varying conditions, other possibilities may be 
considered. Outboard motors, mounted on brackets 
on the barges or on small wooden boats designed to 
nest in the barges, would be satisfactory for small 
loads but probably not for tanks weighing more than 
about 30 tons. An endless cable or ski-tow arrange¬ 
ment would presumably provide the most efficient 
use of power and could be considered in more detail, 
but would need equipment on both shores of the 
water to be crossed. Paddle or propeller drives using 
power take-off from the tanks themselves could be 
developed, as could removable fins or paddles on the 
tank treads. 

The carrying method outlined here appears to be 
particularly practical and flexible. It would have 
great value in ferrying to or from a gradually shoal¬ 
ing river bank, for the tanks cotdd be slung from the 
A-frame so that they would not only launch them¬ 
selves but would lighten the draft of the whole unit 
in shallow water. 4 * 17 


i' See following section. 


>- >5 AMPHIBIOUS PADDLE-WHEEL 
TOWBOAT 

In May 1941, designs were prepared for an am¬ 
phibious paddle-wheel towboat which could cross 
land and operate in water, 8 and could be used on 
towing barges proposed for ferrying tanks weighing 
as much as 90 tons. 1 

One design is shown in Figure 24. This calls for 
constructing the towboat in two longitudinal, mir¬ 
ror-image halves for easier handling and transport. 
Each half would be 20 feet long and 7 feet 10 inches 
wide, and would include a paddle wheel at the side, 
l he wheel would be chain-driven by a 4-cylinder, 
55-lip Ford automobile engine, with the controls 
brought to the inner side. The two units would be 
joined by means of special connectors. 

In an alternate design, as shown in Figure 25, the 
paddle wheel would be fully contained within the 
hull of each unit, giving an over-all width of 5 feet. 

In either case, although the boat is very heavy and 
requires two motors to maintain maneuverability, it 
should provide good towing power. 

12.16 TANK LANDING SHIP 

A 600-foot transport vessel was designed in May 
1941 to serve as a tank landing ship. 8 As shown in Fig¬ 
ure 26, it would accommodate up to 82 30-ton tanks 
or a lesser number of amphibious tanks on a tank 
platform deck and in the hold. 

A launching ramp at the after end of the ship 
would permit the tanks to be landed on suitable piers 
or barges, or amphibious tanks could be launched 
directly into the water. 

i For a description of these barges, see preceding section. 
































































































228 


BRIDGE, PONTON, AND FERRY DESIGNS 


I'lie vessel would have a beam of 65 feet, a draft of 
22, a depth of 42, and a speed of 20 to 22 knots. Anti¬ 
aircraft guns would be mounted on the weather deck, 
and catapults would be provided to launch fighter 
planes. Shop facilities would be provided for repairs 
on the tanks during transport. 17 

This project was not carried beyond the prepara¬ 
tion of rough plans, primarily because of a lack of 
interest by the Armed Services and because of their 
failure to agree on which branch should bear the re¬ 


sponsibility, if any, for transporting tanks from ship 
to shore. At the time of this project, with no apprecia¬ 
tion yet displayed by the Services for the actual re- 
quirements of an amphibious operation, Navy offices 
advised NDRC that the Army had not signified any 
intention to land tanks from ships, while Army offices 
asserted that such a requirement was a Navy respon¬ 
sibility. The research project was accordingly ter¬ 
minated. 

Unknown to NDRC at the time, however, the 



Figure 24. Amphibious paddle wheel towboat, plan 1. 










































































































































LANDING PIER 


229 


basic idea of the tank landing ship had already been 
worked out by the British in the design of the LST 
(1) (Landing Ship, Tank, Class 1), and incorporated 
in the HMS Thruster and Boxer. Later, the LST(l) 
was redesigned and the idea of the tank landing ship 
found its final expression in the LST(2), which, at 
British insistence, was put into production by the 
U. S. Navy. The development of amphibious tanks is 
described in Chapter 9. 

u n LANDING PIER 

For the landing of 30-ton tanks at sites where tides 
up to 20 feet exist, a pier was designed with the main 


carrying members consisting of H-10 truss sections 
joined by connectors already developed for use in a 
ponton bridge, and the erection floats being the 
available standard 25-ton aluminum pontons." The 
general plan is shown in Figure 27. 

A section of pier with a length slightly more than 
50 feet and with one bent attached would be floated 
into position. A crane operating on the already com¬ 
pleted portion of the deck and a floating derrick 
would then raise the section from the pontons to the 
final elevation in the pier. After a connection was 
made to the completed portion and while the heavy 
end was still held by the derrick, the columns (until 
then in a raised position) would be dropped to the 



Figure 25. Amphibious paddle wheel towboat, plan 2. 













































































































230 


BRIDGE, PONTON, AND FERRY DESIGNS 


bottom, and pins inserted at the transom ends, d he 
next section of the pier would then float into 
position. 15 

12.18 QUAY REPAIRS 

With the expectation that the U. S. Army would 
probably be called upon to put back into service 
many quays that were severely damaged by the with¬ 
drawing enemy, a study was made of the most useful 
designs. a The most practical is shown in Figure 28. 

Wide-flange steel shapes, serving as piles, would be 
driven on 16-foot centers in two directions. The piles 
would next be flame-cut to the desired elevation and 
caps, prepared in advance, placed on the piles and 
welded to take the entire load. The piles would be 
located with their flanges normal to the quay face in 
order to permit the easy installation of welded brac¬ 
ing at low tide. In cases where the pile bearing is 
inadequate, short pieces of the same section can be 
welded to the pile to provide added bearing. 


The same size members which serve as piles can 
also be utilized as girders and welded to the column 
caps. A splice can be applied to permit the use of odd- 
length pieces of girder. 

A number of alternate floor systems were con¬ 
sidered: 

1. A design using timber stringers and timber 
deck. 

2. A design using steel stringers and an open steel 
floor. 

3. A design using a reinforced-concrete deck on 
rein forced-concrete stringers. 

4. A design similar to 3, except that a lightweight 
joist is encased in the beam. This will support the 
forms and carry the wet concrete, thus eliminating 
the need for other form support. 

5. A design using a reinforced-concrete deck on 
steel stringers. Corrugated iron sheets will serve as 
bottom forms for the slab and will be left in that 
position. 




±: -ft 


^ J X1X1XIXI 

4X1X1XJX4 


IXlXlXl 1X1 
IXlXlXl (X 
IXlXlXl XI 



TRACK 


I-^ 


-1 (X) 

'units 


TANK PLATFORM DECK PLAN 



Figure 26. Landing ship for amphibious tanks. 



















































































































QUAY REPAIRS 


231 


With any of these suggested floors, the basic design 
will serve with a tidal range of 10 to 12 feet and a 
low-water depth of as much as 30 feet, and may be 
contrasted with the British V-type trestle which was 
considered for the same service and which has a cor¬ 
responding low-water depth of 16 feet. 


Quays and piers similar to the suggested design 
have been satisfactorily used for a number of years, 
and experience with them indicates that they are 
adequate for docking large ships. This structure will 
support a medium tank and any wheeled vehicle 
except a loaded tank retriever. 16 





Fic.ure 27. Design of landing pier. 








































































































VARIES 


232 


BRIDGE, PONTON, AND FERRY DESIGNS 





DETAIL OF PILE CAP 

CAP TO BE ASSEMBLED AND WELDED IN SHOP 
AFTER DRIVING PILE, CUT AT ESTABLISHED LEVEL, 
PLACE AND FIELD WELD CAP, ERECT GIRDER 
AND FIELD WELD TO CAP. 


Figure 28. Proposed structures for quay repairs. 









































































































































































































































































Chapter 13 

TESTS OF BRIDGE COMPONENTS 


Summary 

A nalysis of balk, balk fasteners, and bolts used or 
contemplated lor military bridges was conducted 
at the request of the Engineer Board of the U. S. Army 
Corps of Engineers. 

Standard laboratory tests were performed on 
Douglas hr balk intended for ponton bridges, steel 
balk with and without web holes, and several designs 
of aluminum balk, including hollow balk and balk 
reinforced with internal ribs and traffic plates. 

Similar tests were performed on welded steel, cast 
steel and bronze balk fasteners, and on heat-treated 
bridge bolts. a 

13.1 TESTS OF DOUGLAS FIR BALK 

Samples of Douglas hr balk intended for ponton 
bridges were tested as beams and for compression, 
both dry and after immersion in water. The beam 
tests were made on full-size balk with third point 
loading, and measurements were made of mid-point 
deflection and top fiber strains. These showed an 
average ultimate strength of 8,500 psi and a modulus 
of elasticity of 1,900,000 psi from mid-point deflec¬ 
tion and of 2,159,000 from top fiber strain. 

Smaller samples were tested in compression paral¬ 
lel to the grain, with some tested dry and others after 
being immersed in water overnight. This gave an 
average ultimate strength of 6,030 psi and a modulus 
of elasticity of 1,925,000 psi for the dry samples, and 
3,650 and 1,860,000 for the wet samples. A gain in 
moisture of about 9 per cent by weight was found 
to decrease the strength and stiffness considerably. 
No correlation was found, however, between per cent 
increase in moisture and per cent decrease in strength 
and stiffness. Similarly, an effort to correlate specific 
gravity to strength and stiffness gave no definite rela¬ 
tionship. The number of annular rings per inch does 
not prove to be related in any orderly way to strength 
and stiffness. 

Other tests seemed to indicate that balk with the 
growth rings vertical have slightly higher propor¬ 


a These tests were conducted by the Drexel Institute of Tech¬ 
nology, Philadelphia, Pa., under O.SRI) contract OEMsr-41. 


tional limits and moduli of elasticity, but slightly 
lower ultimate strengths than those with rings 
horizontal. 1 

1 TESTS OF ALUMINUM BALK 

Aluminum Alloy (R305-T315) 

In order to determine their usefulness as balk for a 
lloating bridge, welded members of aluminum alloy 
R303-T315 b were tested for yield strength and ulti¬ 
mate strength. 

Of eight samples, five failed at stresses of 6,220 to 
8,200 psi with the break at the edge of a % 6 -inch 
weld, while three failed at stresses of 6,550 to 7,410 
psi with the break in the weld. In shear tests, five of 
six samples failed at the edge of the weld at stresses 
of 3,200 to 4,020 psi. In all these cases the parent 
metal failed at stresses exceeding 33,000 psi. One 
plain specimen of the alloy gave a yield strength of 
73,400 psi, an ultimate strength of 77,200, and a 
modulus of elasticity of 10,000,000 psi. 4 

Beams With and Without Web Holes 

A steel beam with lightening holes cut in the webs 
to reduce dead weight was investigated to determine 
the effect of the holes on beam deflection. The holes, 
3 1/2 inches in diameter, were cut along the center line 
of the web at 6 i / 2 inches center to center, in an 8-inch 
WF 17-pound steel beam. The beam was tested both 
before and after the holes were made. 

The solid web was loaded with 20,000 pounds at a 
calculated fiber stress of 43,200 psi without giving 
any permanent set. The web with holes was tested 
up to 25,000 without failure and without permanent 
set upon return to initial loading. 

Deflection measurements showed an increase of 
center deflection for the beam with holes of about 
0.01 inch per 8,000 pounds over the beam without 
holes. The beam with holes held the maximum load 
imposed without apparent distress. 

The total load was limited by a desire to keep 
Hange-bending stresses below the yield strength 


b Manufactured by Reynolds Metals Company. Test welds 
made by Allison Steel Manufacturing Company, Phoenix, Ariz. 

233 








234 


TESTS OF BRIDGE COMPONENTS 


values. I'he shearing stress in the web due to the 
largest load placed on the beam without holes was 
therefore only 5,430 psi. This is less than one-half 
of the peacetime allowable shear stress of 11,000 psi 
in the webs of highway bridge girders, which in turn 
is far below the value which causes buckling failure. 5 

Balk (24S-T) with Internal Rib 

A normal 9x9-inch aluminum balk of alloy 24S-T C 
was subjected to a beam test of the balk, tension and 
shear tests of the welds, and a tension test of the 
aluminum. The balk (Figure 1) was made from two 
aluminum channel-shaped extrusions, welded to 
form a box-shaped section. The top has six external 
longitudinal ribs and one internal longitudinal rib. 
In the external ribs, indentations are pressed 4 i / 2 
inches center to center. These indentations are oppo¬ 
site in alternate rows, staggering those in the other 
three rows, and are of such a depth that the inside 
of the top becomes level directly beneath them. 

As the loading increased, an apparent elastic limit 

c Fabricated by the Allison Steel Manufacturing Company, 
Phoenix, Ariz. 




Figure 1. Cross section of aluminum deck balk with in¬ 
ternal rib, with details of beam test setup. 


was observed between 30,000 and 32,000 pounds. No 
visual signs of failure were noticed below 46,000 
pounds. Definite failure occurred at 51,800 pounds, 
with buckling of the webs and the upper plate. 

In tension tests, the weld failed under an average 
breaking load of 8,170 pounds or 4,090 pounds per 
inch of weld, in contrast to 21,680 psi lor the parent 
metal. In shear test, the weld failed under an average 
breaking load of 12,550 pounds or 3,150 pounds per 
inch of weld, in contrast to 33,730 psi lor the parent 
metal. 

In tension tests of the aluminum, the yield 
strength was found to be 50,700 psi, the ultimate 
strength 68,000, and the elongation was 14.21 per 
cent in 8 inches. 11 

Normal Balk (6 1S T) with Reinforcing Plates 

A normal 9x9-inch aluminum balk of 61S-T alloy 
was subjected to a beam test of the balk, tension and 
shear tests of the weld, and a tension test of the 
aluminum. 

The balk was made from two channel-shaped ex¬ 
trusions, with plates riveted to the top and bottom, 
symmetrical with the center of the balk and extend¬ 
ing on either side. The rivets on the plates were stag¬ 
gered. T he channels were then welded to form a box¬ 
shaped section (Figure 2). c 

As the load was applied for the beam test, the first 
indication of permanent set came at 34,000 pounds, 
with a definite set observed at 35,000 pounds. Sudden 
failure came at 50,900 pounds, with buckling of the 
top plates and webs. 

In tension tests of the weld, failure occurred at an 
average of 4,450 pounds per inch of weld, in contrast 
to 23,000 psi for the parent metal. In shear tests, the 
weld failed at an average of 2,690 pounds per inch 
of weld, in constrast to 27,700 psi for the parent 
metal. 

In tension tests of the aluminum, the average ulti¬ 
mate strength was found to be 43,600 psi and the 
average elongation 9.92 per cent. 10 

Normal Balk (61S-T) with Internal Rib 

A 9x9-inch aluminum balk e made from two alumi¬ 
num channel-shaped extrusions of alloy and welded 
to form a box-shaped section (see Figure 1) was sub¬ 
jected to a beam test of the balk, tension and shear 
tests of the weld, and a tension test of the aluminum. 

The top has six longitudinal external ribs and one 
internal rib. In the six external ribs, indentations 












































TESTS OF ALUMINUM BALK 


235 


1% inches long are pressed 4 i / 2 inches center to cen¬ 
ter. These indentations are opposite in alternate 
rows, staggering those in the other three rows, and 
of such a depth that the inside of the top becomes 
level directly beneath the indentations. The plane 
of the ribs in the two outer rows is slightly above 
that of the ribs in the four inner ones. 

As the loading was increased, an apparent elastic 
limit was observed at approximately 32,000 pounds. 
Failure occurred with a 40,000-pound load, with defi¬ 
nite buckling in the webs and in the upper plate. 

In tension tests of the weld, each specimen failed 
in the weld with an average value of 1,440 pounds 
per inch of weld. Those welds showed very poorly 
fused metal, which explains the low values of the 
breaking loads. 

In shear tests, average shear value was 2,440 
pounds per inch of weld, with a minimum of 2,340 
pounds per inch. 

In tension tests of the aluminum, the average ulti¬ 
mate strength of the specimens was found to be 
42,970 psi and the average elongation 10.96. 8 


Heavy Balk (61S-T) 

A heavy 9x9-inch aluminum balk of alloy 61S-T C 
was subjected to three sets of tests, including beam 
tests of balk, tension and shear tests of welds, and 
tension tests of the aluminum. 

The balk (Figure 3) was made from two channel¬ 
shaped extrusions welded to form a box-shaped sec¬ 
tion. Fhe top surface has live longitudinal ribs in 
which 11^-inch indentations are pressed opposite 
each other in alternate rows; those in the other three 
rows are staggered; and all are of such a depth that 
the inside of the top becomes level directly beneath 
them. I he plane of the two outer ribs is slightly 
above that of the three inner ones. 

In the initial group of tests, the first indication of 
a permanent set under increased loading came at 
26,000 pounds, with a definite, measurable set after 
the 30,000-pound load. No visual signs of failure 
were noticeable below 38,000 pounds, and buckling 
occurred in the webs and upper plate at 40,000. 

The weld failed in tension tests at an average of 
2,740 pounds per inch of weld, in contrast to 14,150 



5 '- 6 "- 


, 3 

- 3 - 10 - 


— 5 '- 6 "- 
R/F PLATES 


J7 






- 7 '- 5 ! 

I4'-| 0 | 

4 


71 


' 






V7777 



Figure 2. Aluminum balk reinforcing plate, with details Figure 3. Heavy aluminum balk (61 S-T), with details of 

of beam test setup. beam test setup. 



































































































236 


TESTS OF BRIDGE COMPONENTS 


psi for the parent metal, and in shear tests at an aver¬ 
age of 2,910 pounds per inch of weld, in contrast to 
28,400 psi for the parent metal. 

The average yield strength of the aluminum was 
found to be 39,500 psi, the ultimate strength 41,600 
psi, and the per cent of elongation 11.30 in 8 inches. 7 

In the second series of tests, the first indication of 
a permanent set under increased loadings came be¬ 
tween the 28,000- and 30,000-pound loads, with fail¬ 
ure at 40,200 pounds marked by buckling of the webs 
and top plate at one of the loading points. 

Under tension, the weld failed at an average break¬ 
ing load of 9,670 pounds or 4,800 pounds per inch 
of weld. In comparison, the parent metal failed at 
23,900. In shear tests, the weld failed at an average 
breaking load of 10,500 pounds or 2,620 pounds per 
inch of weld. The average unit stress in the parent 
metal at failure was 26,200 psi. 

In a tension test of the aluminum, the results gave 
an average ultimate strength of 42,500 psi and an 
elongation of 10.88 per cent in 8 inches. 9 

Used Balk 

A used welded aluminum balk reported to have 
had approximately 1,600 passes of an M-4 tank with 




5 - 6 "- 


P P 

1!U 



Figure 4. Used aluminum balk, with details of beam test 
setup. 


steel tracks' 1 was subjected to a beam test of the balk, 
tension and shear tests of the welds, and a tension 
test of the aluminum. 

The balk consists of two aluminum channel-shaped 
extrusions of 61S-T alloy, welded to form a box¬ 
shaped section (Figure 4). 

14ie first indication of permanent set came at or 
near 19,000 pounds. At a load of slightly less than 
26,000 pounds, failure occurred with the buckling 
of the top flange at one of the loading points. This 
buckling increased to such an extent that only 19,000 
pounds could be maintained by the balk. At this 
final load, the center line deflection was 3.05 inches, 
with a set of 0.90 inches upon release of the load. 
Since the buckling of the top flange occurred before 
the yield strength stress was developed, the balk had 
apparently not been damaged by its previous usage. 

The weld failed under tension at an average of 
6,620 pounds per inch of % 6 -inch weld, with a mini¬ 
mum of 1,680 and a maximum of 3,750, in contrast 
to an average of 13,590 psi, a minimum of 8,820, and 
a maximum of 19,250 for the parent metal. Under 
shear, the weld failed in two of four samples at an 
average of 980 pounds per inch of % 6 -inch weld, in 
contrast to an average of 10,270 psi for the parent 
metal. 

Tension tests on the aluminum gave an average 
yield strength of 39,680 psi, a maximum stress of 
42,500, and a 9.37 per cent elongation in 8 inches. It 
was noted that the wearing of the top flange of the 
balk did not affect its maximum stresses, which were 
slightly greater than the maximum values for speci¬ 
mens taken from the bottom flanges. 6 

Balk with Traffic Plate 

A welded aluminum balk with steel traffic plate 6 
designed for use on bridges and other structures was 
submitted to beam tests of the balk itself, tension and 
shear tests of the welds, tension tests of the aluminum 
and the traffic plate, and pull tests on the balk lugs. 

The balk (Figure 5) is composed of a steel traffic 
plate riveted to a box-shaped section made from two 
aluminum extrusions of alloy 61S-T joined by welds 
formed by a Lincoln carbon arc machine, tornado 
head. 

Fhe beam tests on a 15-foot simple beam indicated 
an apparent elastic limit at or near 22,000 pounds, 

6 Designed by Sparkman & Stephens, Inc., New York, N. Y„ 
and fabricated by the Allison Steel Manufacturing Company, 
Phoenix, Ariz. 









































TESTS OF BALK FASTENERS 


237 


with a center deflection of 3.75 inches under a maxi¬ 
mum load of 30,600 pounds. Deflection is a straight- 
line function of the load until the elastic limit of the 
steel is reached. Further analysis indicated that the 
permanent deformation of the steel prevents the 
aluminum in the vicinity of the steel plate from 
returning to its original length. The stresses in the 
aluminum do not reach elastic limit values even at a 
beam load of 28,000 pounds. 

In accordance with beam theory, the unit strain in 
the aluminum, measured at various distances from 
the calculated neutral axis, varies directly with the 
distance. A shift in the position of the neutral axis is 
noted first at the 22,000-pound load and, as expected, 
is toward the stronger side of the beam and away 
from the compression side, where failure starts. 

Tension tests 90 degrees to the weld resulted in 
five failures in the weld, with a minimum value of 
2,170 and an average of 4,200 pounds per inch of 
weld, and eight failures in the plate. Tension tests 
45 degrees to the weld gave a minimum shear value 
of 1,270 and an average of 2,110 pounds per inch of 
weld. 

Tension tests made with a Huggenberger strain 
gage on specimens of aluminum and traffic plate gave 
the following results: 


Specimen 

Yield 

strength 

(psi) 

Maximum 

(psi) 

% elonga¬ 
tion in 8" 

E 

Aluminum 

36.700 

10,500 

9.62 

10.600,000 

Traffic plate 

36,300 

53,300 



Traffic plate 

39,200 

54,500 

25.5 



Tests were performed to determine the pull in 
direct tension which the intermediate lugs would 
resist. One specimen failed at a load of 37,400 pounds 
when the weld metal connecting the lug and the two 
bolts on one side of the fitting sheared off. The sec¬ 
ond test was stopped after the other lug had resisted 
a pull of 37,500 pounds without failure. 3 

Hollow Metal Balk 

Tests performed on samples of hollow metal balk 0 
proposed as lightweight beams for use in ponton 
bridges and other structural devices showed that the 
members are too weak in shear to allow the develop¬ 
ment of beam strength. 

The hollow balk weighs 8$/ 4 pounds per foot and 


is in the general shape of a hollow I section. The 
flanges consist of channels 3.30 inches back to back 
of flanges. The web consists of two plates, 0.05 inch 
thick and spaced 1.78 inches apart, bent to fit around 
timbers lx3-inch used to shape the flanges. T he chan¬ 
nels are tack-welded along the edges to the web metal 
and also are spot-welded through the top of the 
flange. The web has holes 5.5 inches in diameter 
on 9-inch centers, the two side plates bent in and 
welded together to form the holes. 

Strain measurements showed that the material 
does not bend as a beam, and finally fails due to 
shear, as indicated by the buckling of the web metal 
between the holes, the distortion of the holes, and 
the flat straight shape of the member between load¬ 
ing points. Tension tests showed a definite yield 
point for the flange, marked by both scaling and the 
drop of the beam at 27,300 psi. T he ultimate stresses 
are 41,700 psi for the flange and 47,200 for the web. 2 

13.3 TESTS OF BALK FASTENERS 


Three types of balk fasteners were examined at the 
request of the Engineer Board, and tested for resist- 



Figure 5. Aluminum balk with steel traffic plate, with de¬ 
tails of beam test setup. 


e Manufactured by the Rafter Machine Co., Belleville, N. J. 












































TESTS OF BRIDGE COMPONENTS 


2.'58 


mice to various loads and lor operation of the fasten¬ 
ing mechanism. 

Welded Steel Balk Fasteners 

Two specimens were subjected to loads up to 
13,500 pounds. One specimen began to yield locally 
near the hook at 11,500 pounds and failed at 13,500. 
When the end of the locking pin was ground to a 
conical point to facilitate the drifting together of the 
parts, the mechanism operated satisfactorily after 
holding a load of 13,000 pounds. The second speci¬ 
men held a maximum load of 13,100 pounds, with 
the mechanism operating satisfactorily throughout. 1 - 

Bronze Balk Fasteners 

Specimen fasteners for 10- and 25-ton ponton 
bridges were tested for maximum load and for work¬ 
ability of the ratchet mechanism after successive 
loads. The fasteners designed for the 10-ton bridge 
failed under an average load of 11,000 pounds, with 
the mechanism locking at 9,500. Those for the 25-ton 
bridge failed under an average maximum of 18,290 
pounds, with the mechanism locking at 13,330. 1:1 

Cast Steel Balk Fasteners 

Five cast steel fasteners were tested for maximum 
load and for workability of the mechanism, with fail¬ 
ure occurring at an average of 16,900 pounds. Each 
failed suddenly at a section near the hook. 14 

13.4 TESTS OF BRIDGE BOLTS 

Heat-Treated Bolts 

Heat-treated steel bolts f designed for use in the 
light H-10 portable bridge were tested with two dif¬ 


ferent types of threads. The bolts have a nominal 
diameter of 1 1 / 4 inches, an over-all length of 22 inches, 
a thread length of 3 inches with five threads per inch, 
and a square head 1 inch high and D% 6 inches flat 
diameter. 

Ten bolts, five made with Acme threads and five 
with Dardelet threads, were supplied with mild steel 
hexagonal nuts and tested full-size for yield point 
and ultimate strength with a distance of 19 inches 
from under the head of the bolt to the inside bearing 
of the nut. This is the distance generally used in 
service. 

With Acme threads, all bolt failures were in ten¬ 
sion at the minimum cross section next to the nut, 
with a cross-section area of 0.811 square inch. The 
bolts failed at an average of 154,240 psi, giving an 
average maximum unit stress of 154,240/0.811 or 
190,000 psi. 

With the Dardelet threads, three failures occurred 
in the nut threads at a maximum unit stress of 
114,400, 143,900, and 149,600 psi, respectively, one 
in the bolt threads at 166,700, and one partly in the 
bolt threads and partly in the nut threads at 165,400. 

If heat-treated bolts are used with the H-10 bridge, 
it is recommended that the bearing lugs of the bridge 
be torch-hardened and the hole reduced from H/ 2 to 
13/g inches. 

I he threads ol the 114-inch mild steel nuts as sup¬ 
plied were found to shear out at an average maxi¬ 
mum load of 146,750 psi. To realize a value equaling 
that of the bolts, the nuts should be made 2 inches 
long (\y A inches if heat-treated). 15 


f Manufactured by the Lainsou & Sessions Co., Cleveland. 
Ohio. 





Chapter 14 

TORPEDO PROTECTION FOR MERCHANT VESSELS 


Summary 

A r the request of the U. S. Maritime Commission, 
- improved wire nets have been developed to pro¬ 
tect merchant vessels from torpedo attack. One type 
of net, weighing 14 tons, can be carried by ships 
under way with the aid of handling gear weighing 
16 tons, and is able to catch 30- to 35-knot torpedoes 
by their tails. Another, which can either be carried 
by the ships or be placed around them while moored, 
is able to stop 45- to 50-knot torpedoes by their heads. 

New net designs have been prepared, new wire 
strand specifications made, and new streamlined 
metal clips devised to give maximum efficiency, 
maximum useful life, and minimum drag through 
the water. The drag of a Liberty ship at 11.5 knots 
has been reduced from about 1.6 knots to about 1.3 
knots, thus permitting such a vessel to maintain con¬ 
voy speed in a 10-knot convoy, with her nets down. 
The reduction in shaft horsepower absorbed by the 
net is about 110, from 900 slip to 790 slip. 

Electrically energized cables have been developed 
for use with these nets as a protection against mag¬ 
netic torpedoes. The energized cables are designed 
to produce a magnetic field which will explode such 
torpedoes before they reach their target. 

All these devices have been tested full scale in a 
limited number of field trials and appear to operate 
successfully. 

There is no doubt that ship losses could have been 


••> Project “Merchant,” NO-158. 


averted had net protection been developed 2 years 
earlier, had ships been equipped with this gear, and 
had ship’s masters been compelled to use it in waters 
where submarines might be operating. With the 
latest type of net developed in this investigation, 
ships can remain at anchor in comparative safety 
or can move in 10-knot convoys. 

Although the various laboratory and field tests left 
little doubt that the newly developed nets were con¬ 
siderably superior to the older type, the new device 
was not placed in production. It was fell by respon¬ 
sible officers of the U. S. Maritime Commission that 
any change of design would delay delivery, necessi¬ 
tate the scrapping of much material, and increase 
the cost of manufacturing. In addition, it was de¬ 
cided, submarine warfare did not at that time war¬ 
rant such a change. 

The need for a defense against magnetic mines was 
not considered to be urgent, and consequently no 
practical applications of the electrically armed cable 
were made. 

Despite the added effectiveness of the improved 
clip designs, these were not used because of the deci¬ 
sion that their adoption woidd result in scrapping 
both machinery already delivered and old-style clips 
already manufactured, and in an increased cost of 
manufacture, without a sufficient degree of improve¬ 
ment. 

The Coordinator of Ship Defense Installations of 
the U. S. Maritime Commission has, however, for¬ 
warded to Division 12, with approval, a letter from 



Figure 1. General arrangement of torpedo net defense [TND] and appurtenances. This type is designed to catch 30- to 
35-knot torpedoes, must be operated at speeds above 8 knots to be effective, and is able to catch torpedoes only by the 
tail. 


L L^ 


239 








240 


TORPEDO PROTECTION FOR MERCHANT VESSELS 




Figure 2. Nets streamed on Liberty ship. 


the Director, U. S. Maritime Commission Depots, 
stating that the development expense, some $250,000, 
was justified. 

14.1 THE problem 

Ever since the use of submarines in World War I, 
methods had been sought for efficient protection 
against them, particularly for merchant vessels which 
were unequipped with necessary submarine detect¬ 
ing devices and antisubmarine weapons, and which 
were too slow to evade attack. Early in 1943, when no 
satisfactory solution had yet been found for the 
German submarine campaign in World War II, the 
U. S. Maritime Commission requested assistance in 
developing adequate net protection for EC-2 Liberty 
ships. These vessels were already being equipped 
with Torpedo Net Defense [TND], which had been 
developed by the British as an emergency measure 
in World War II and which was still in a somewhat 
experimental stage. The nets were difficult to handle, 
had a short life, and caused a high water drag, with 
the result that ship’s masters and convoy commo¬ 
dores were often reluctant to stream them, particu¬ 
larly since Liberty ships were consequently slowed 
down by about 2 knots or just enough to be forced 
out of the 10-knot convoys and into the slower 
convoys. 


A research program was consequently set up in 
May 1943 to investigate three protective devices: 13 
(1) a net to catch low-speed (30- to 35-knot) torpedoes 
by their tails, (2) a net to stop, catch, or deflect high¬ 
speed (45- to 50-knot) torpedoes by their tails or heads, 
and (3) a device to give protection against magnetic 
torpedoes. 


b This investigation was conducted by the American Steel 
and Wire Company, New Haven, Connecticut, under OSRD 
contract OEMsr-1077. 


Figure 3. Nets brailed on Liberty ship. 
























PROTECTION AGAINST LOW-SPEEI) TORPEDOES 


241 



Figure 4. New clips designed for antitorpedo nets. 


In the case of complete nets, an attempt was made 
in the design to decrease the net drag at cruising 
speeds, increase the operating life of the mesh 
strands, often limited to one round trip across the 
Atlantic, and simplify the manufacture of the com¬ 
ponents. 4 

n-2 PROTECTION AGAINST LOW-SPEED 
TORPEDOES 

14,21 Procedure 

Nets first went into service on American Liberty 
ships in November 1942. These were similar to those 
currently being installed on British merchant vessels, 
with a complete defense consisting of two nets, one 
provided for each side of the ship (Figure 1). Each 
net 6 is about 270 feet long and extends below the 
water surface approximately to the draft of the ship. 



Figure 5. Recovery of low-speed torpedo fouled in net. 



















242 


TORPEDO PROTECTION FOR MERCHANT VESSELS 



Figurf. 6. Sequence of views showing approach of low-speed torpedo and its capture by the tail in a diamond mesh 
weave net. Successive frames reading downward in each column show torpedo nose passing through the mesh until tail 
is caught. White line crossing the lower left-hand corner of each frame is the after guy of the forward boom. White dis¬ 
turbance in water entering at right of frame is wake of net, the forward end of net being toward left. Torpedo was held 
until its fuel was exhausted. These pictures represent alternate frames taken from moving picture film at speed of 
16 frames per second. Period covered by this sequence is approximately 4 seconds. 


When the net is streamed (Figure 2), it is supported 
by Blondin rollers on a Blondin cable which is at¬ 
tached to the ends of tubular steel booms so that the 
net takes a vertical position about 50 feet from the 
ship’s side. 

These early nets are composed of % 6 -inch dia¬ 
meter, 19-wire strands with a minimum breaking 
strength of 14,500 pounds, woven together and at¬ 
tached by riveted clips to form a diamond-shaped 
mesh 60 inches long and 30 inches high. The strands 
are also clipped to four boundary ropes—the head- 
rope above, the footrope below, the luff rope forward, 
and the leech rope aft. 

The Blondin cable supports the net so that, with 
the assistance of a kite attached forward and a drogue 
attached aft, the net is held in a vertical position 
when moving through the water. Each boom sup¬ 
porting the net is held in a horizontal position by a 
topping lift reeved through blocks at tlie masthead. 

When the net is brailed or taken in, a brailing rope 


gathers the net and its roller supports to the end of 
the after boom; both booms are then raised vertically 
until they engage a device which secures them to the 
mast arm, and the nets hang free from a point about 



Figurf 7. Hole in diamond weave net which has heen 
struck by high-speed torpedo. 













PROTECTION AGAINST LOW-SPEEI) TORPEDOES 


243 



Figure 8. Diagrams of diamond, tilted diamond, and tilted reverse diamond weave. 


70 feet above the deck, where they are lashed in posi¬ 
tion by means of a wire rope gasket (Figure 3). 

The nets are streamed along the Blondin by means 
of a towrope when the booms are lowered sufficiently 
for the nets to clear the decks. 


The necessary power for these operations is de¬ 
rived from the ship’s cargo winches. 

Some of these nets already in service were exam¬ 
ined and their components subjected to laboratory 
test. It was found at the U. S. Maritime Commission 




























































244 


TORPEDO PROTECTION FOR MERCHANT VESSELS 



Figure 10. Details of seams in tilted diamond weave. 


Brooklyn Depot that the most noticeable failures 
were due to the corrosion of the strand and the con¬ 
necting clips, and to the strands being pulled from 



Figure 11. Laboratory setup to determine wire strand 
necessary to entangle and hold torpedoes. Test wire, 
shown held firmly in frame, is moved into propeller. 


tlie boundary rope clips during service. The strand 
wires were failing from fatigue, particularly at the 
points where they were clipped together to form the 
mesh. 

These findings were confirmed and amplified by 
laboratory tests which showed that the clips used in 
the net were unsatisfactory. They were ungalvanized 
and corroded rapidly. They had to be riveted to¬ 
gether—a process which distorted, mashed, and weak¬ 
ened the strands. The slip value between the strand 
and the clip was not constant, varying greatly in the 
“break-away” value and in the “steadying-down” 
value. 

Accordingly, three new types of galvanized, 
welded, streamlined clips—Types 122 and 122-A as 
mesh clips and Types 123 and 124 as boundary clips 
(Figure 4)—were developed and incorporated in a 
net with standard 60x30-inch mesh which was in¬ 
stalled on a Liberty ship for test. With the ship 











































PROTECTION AGAINST LOW-SPEED TORPEDOES 


245 



Figure 13. Design E was tested as 14 -inch-diameter, 19- 
wire strand and as 9/32-inch-diameter, 19-wire strand ex¬ 
panded weave, each section 11 inches square. 


under way, 31-knot torpedoes equipped with colli¬ 
sion heads were fired at the net. The ability of this 
net to stop torpedoes was noted, as was the drag of 
the net and the general arrangement and t ype of gear 
used to support and operate the nets. 


14.2.2 


Results 


The new clips functioned satisfactorily while the 
nets were catching 31-knot torpedoes by fouling their 
propellers and tail assemblies (Figures 5 and 6). In 
those cases of failure which did occur in the test, the 
failure of the mesh strands at the leech rope was 
responsible. 

Use of the new clips reduced the drag of two nets 
from 1.66 knots to about 1.30 knots. Ship’s speed, 
normally 11.5 knots, increased from 9.9 knots with 
the standard net to 10.2 knots with the new net. The 
slip values of the new clips are relatively constant. 

1 'he mechanical gear used to support and operate 
the net was found not conducive to long rope life, 
and the arrangement of snatch blocks results in some 
hazard to personnel when the net is streamed in 
heavy weather. 


Figure 12 

Design A was tested as 11/32-inch-diameter, 19-wire 
strand, 16-inch-diameter swaged grommets and as 


inch-diameter, 7-wire strand, 16-inch-diameter swaged 
grommets. 

Design B was tested as 0.282-inch diameter, 0.094-wire, 
combination 12- and 16-inch-diameter hanclwoven grom¬ 
mets and as 3/16-inch, 7-wire strand, combination 12- 
and 16-inch-diameter swaged grommets. 

Design C was tested as 0.312-inch diameter, 0.104-wire, 
12-inch-diameter swaged grommets. 

Design D was tested as No. 000 i/g-wire, lOxlO-inch welded 
reinforcing mesh. 
































































2* 


TORPEDO PROTECTION FOR MERCHANT VESSELS 



Fzccxt. 14 Setut : r >i: ;e-'i> «.>n proposed net designs. Inset shows, dummy torpedo striking at 45 knots. 






















PROTECTION' AGAINST HIGH-SPEED TORPEDOES 


247 


14 - 2 - 3 Conclusions 

From these investigations, it appears that a net can 
be manufactured to provide excellent defense against 
30- to 35-knot torpedoes by catching them by the tail. 
The new clips adequately support the net strands 
and give constant slip values so that the torpedo can 
be gradually slowed and then finally stopped. The\ 
should increase the life of the strands and, since they 
are streamlined, they permit at least slightly higher 
ship’s speed. 

The mesh strands should be galvanized to reduce 
corrosion, and they should be dead-ended at the leech 
rope. An 1 % 2 ‘ inc h diameter strand was recom¬ 
mended. 

Although the mechanical gear used with the nets 
in these tests was not altogether satisfactory, it was 
decided that under the actual conditions prevailing 
it was not desirable to make changes. 

Certain general specifications can apply to the 
clips, strands, and mesh of nets: 

1. The clips should allow enough strand slip to 
slow the torpedo gradually, and their built-up hold¬ 
ing power must then be sufficient to stop the torpedo. 

2. The clips securing the mesh strands to the 
boundary ropes must allow the strands to slip when 
the torpedo impact forces reach them, but they must 
not allow slippage during normal handling or usage 
in a seaway. 

3. The strands must have sufficient strength to ab¬ 
sorb all energy remaining from the impact after a 
portion is dissipated by clip slippage. 

4. The strands must also have sufficient flexibility 
to become properly enmeshed in the torpedo tail as¬ 
sembly, and sufficient toughness and abrasion resist¬ 
ance to survive the entanglement. 

5. For improved operating life, the mesh strands, 
brail, and towing ropes should be impregnated with 
lubricant. 

14.3 PROTECTION AGAINST HIGH-SPEED 
TORPEDOES 

1431 Procedure 

In the first phase of this investigation, tests showed 
that an improved net could successfully stop rela¬ 
tively low-speed (30- to 35-knot) torpedoes by en¬ 
tangling their propellers. It then became desirable 
to perfect similar methods for protection against 



Figure 15. 27-knot torpedo striking expanded weave net 
with ship and net static. 


relatively high-speed (45- to 50-knot) torpedoes. This 
was more difficult. 10 

Field tests quickly showed that at torpedo impact, 
the mesh strands were sheared by the propeller be¬ 
fore they could entangle the propeller blades and 
shafts and bring it to a stop (Figure 7). 

Several different types of diamond mesh, tilt dia¬ 
mond mesh, and reverse diamond mesh panels were 
substituted (Figure 8), and “seams” (Figures 9 and 10) 
were incorporated to absorb the impact more grad¬ 
ually, but these modifications did not offer more than 
minor improvement. In turn, all the contributing 
characteristics which had brought about successful 
tail catches of 35-knot torpedoes were extended in 
proper ratios, but every trial revealed that there was 
insufficient strand strength and net yield to stop the 
torpedo. Additional laboratory tests were conducted 
at the U. S. Naval Net and Fuel Depot, Melville, 
Rhode Island, to determine the minimum wire strand 
which could entangle and hold a high-speed torpedo 
(Figure 11), but it was found that the weight of this 
minimum strand would probably exceed the capacity 
of the ship’s gear and that its towing resistance would 
be unpractically high. 13 

In view of these unsuccessful endeavors, the inves¬ 
tigation turned to the design of nets to catch or stop 
high-speed torpedoes by their heads, and at the same 
time to a study of the use of such nets to protect 
moored vessels as well as vessels under way. 

Improved types of grommet nets and welded rein¬ 
forcing mesh nets (Figure 12) and expanded weave 
nets with wire strand with fixed intersections (Figure 
13) were fabricated and studied in torpedo drop 
tests. 11 Each net was supported horizontally by buoys 
and placed beneath a 3,650-pound Mark 14 dummy 









248 


TORPEDO PROTECTION FOR MERCHANT VESSELS 


torpedo. When this dummy was dropped from a 
height of 90 feet, its velocity at point of impact was 45 
knots 0 (Figure 14). It appeared from these tests that 
an expanded weave net of % 2 "* nc ^ diameter, 19-wire 
strands would withstand this impact. 

Accordingly, experimental nets were constructed 
with % 2 "i nc h an d /{o-inch diameter, 19-wire strands 
and installed for sea tests with torpedoes etpiipped 
with collision heads. 


c A mathematical analysis of the results is contained in refer¬ 
ence 9. 


14 - 3 - 2 Results 

In trial runs 12 with the ship under way, the ex¬ 
panded weave nets successfully caught 47-knot tor¬ 
pedoes without damaging the net (Figures 15, 16, and 
17). Decelerometers attached to each torpedo indi¬ 
cated the impact was absorbed so gradually that it 
was unlikely that the kinetir type of exploder mech¬ 
anism would have been set off. 

In a trial run with the ship dead in the water, the 
expanded weave nets also stopped a 47-knot torpedo, 
and again without damage to the net. 



Figure 16. High-speed torpedo with nose (pointed out by arrow) striking expanded weave net. 



















PROTECTION AGAINST MAGNETIC TORPEDOES 


240 


14 5 5 Conclusions 

The ease with which the expanded weave net 
caught 47-knot torpedoes indicates that faster and 
heavier torpedoes can be caught in this manner with 
a high degree of success. With the use of % 6 -inch 
diameter strand, torpedoes with speeds greater than 
50 knots might be stopped. 

Investigations should be continued on the use of 
slip seams to improve the shock-absorbing qualities 
of the net, on the use of larger mesh to reduce the 
total weight, and on uniform expansion of the mesh 
to reduce drag in the water. 

The expanded weave nets developed in this inves¬ 
tigation are believed to be eminently practical. A 
plan for commercial manufacture has been devel¬ 
oped, and the contractor presents as his “unequivo¬ 
cal recommendation that nets of this proven design 
be placed in use on all cargo ships operating in tor¬ 
pedo-infested waters.” 

144 PROTECTION AGAINST MAGNETIC 
TORPEDOES 

UAl Procedure 

On theoretical grounds, it appeared that a practi¬ 
cal protection against magnetic torpedoes could be 
based on the use of electrically energized cables to 
produce a magnetic field at a safe distance from the 
ship. A torpedo entering this field would presumably 
fire before it reached its target. 

To investigate this possibility, measurements were 
made of the magnetic fields produced by various 
types of cables at different positions around the ship 
and carrying different currents. 14 rhe experimental 
designs were limited by the equipment and facilities 
of a merchant vessel which would carry the protec¬ 
tive device, by the speed and effective destructive 
range of known torpedoes, and by the sensitivity ol 
torpedoes known or believed to be used by the 
enemy. 

Sea trials were made with 1,000-ampere, 15-cycle 
alternating current at 00 volts and with direct cur¬ 
rent. The cable was installed on an EC-2 Liberty ship 
equipped with nets. The torpedoes traveled at 4;> 
knots and at a depth which would allow them to pass 
under both the nets and the keel. They carried de¬ 
tonating heads which released phosphide smoke 
bombs at point of firing. 




Figure 17. High-speed torpedo shown just after impact 
against expanded weave net, when it has swung the net 
around the Blondin as a center. A moment later, the net 
settled into water and the torpedo remained caught in 
the same mesh, 

14 - 4 - 2 Results 

When the cable was armed with 15-cycle alter¬ 
nating current, the oncoming torpedoes fired before 
they reached the net or fired under it. 

When the cable was armed with direct current, 
they fired between the net and the ship or under the 
ship. 

1443 Conclusions 

It was found that alternating current at 15 cycles 
provides a high degree of protection against the type 
of magnetic torpedo used in the field trials, and it is 
believed that lower frequencies will give at least as 
satisfactory performance. 

Numerous alternate types of cable and power 
source may be used to provide the magnetic field 
desired. With 15-cycle current, it is recommended 
that the cable be 1,000,000 cir mils copper, rein¬ 
forced with a steel core and surrounded with a flexi- 













250 


TORPEDO PROTECTION FOR MERCHANT VESSELS 



Figure 18. Three-compartment flotation buoy for static 
net protection against torpedoes. 


hie, wear-resistant insulation. It should be attached 
to the TNI) booms and run from bow to stern, mak¬ 


ing a complete loop around the vessel, independent 
of the nets. The power source should be a 20-kva, 
steam-driven generator to operate at 440 volts, single 
phase, 15 cycles per second, with an output of 45 
amperes, and a transformer to step the voltage down 
to 60 volts, 1,000 amperes. 

Intelligence reports on captured specimens of the 
Italian SIC head and its German counterpart, the 
Pi2C, indicate that these magnetic pistols are readily 
actuated by alternating-current fields of low fre- 
quency. The maximum sensitivity of the SIC is at 
12 cycles per second, and of the Pi2C at 6.5 cycles of a 
sinusoidally varying field. Either a 1,000-ampere, 12- 
cycle current or a 250-ampere, 7.5-cycle current would 
provide a suitable magnetic field for protection 
against these torpedoes. 17 



Ficure 19. Details of trial drogues designed for antitorpedo nets. 


q- llV t- 




















MISCELLANEOUS NET EQUIPMENT 


251 



Figure 20. Underwater photographs of passing small boat propeller. 


PROTECTION OF MOORED VESSELS 

Antitorpedo nets have long been used in harbor 
protection to defend moored vessels against torpedo 
attack. For this purpose the nets are suspended by 
buoys and placed around the vessels or across narrow 
channels. 

From the results of the investigation discussed 
here, it appears that the improved nets, particularly 
the expanded weave net for protection against high¬ 
speed torpedoes, would be particularly useful in this 
static type of protection. Field tests with the ex¬ 
panded weave net showed that it is as effective when 
moored as it is when streamed by a moving vessel. 

To improve static defense, a new flotation buoy 
was produced with ogive ends and three compart¬ 
ments which should be able to withstand machine- 
gun strafing (Figure 18). It provides a means of at¬ 
taching the net which eliminates frictional wear on 
both net and buoy, and its shape provides cpiick 
response to reactions imposed on the net by torpedo 
impact. The new buoy can be knocked down and 
nested during shipment. 12 

J4.6 DETECTION OF TORPEDOES 

A closely allied investigation on sonar equipments 
designed for merchant vessels as automatic, con¬ 
stantly alert detecting systems was conducted simul¬ 
taneously by another National Defense Research 
Committee division. A report on these devices, in¬ 


cluding an analysis of American and British systems, 
is presented elsewhere. <l 

14-7 MISCELLANEOUS NET EQUIPMENT 

In addition to the major developments, the inves¬ 
tigation yielded other devices and recommendations 
for improvements. 

Numerous moving pictures and still photographs 
were taken for instruction of TND Depot personnel. 

Four different types of drogue (Figure 19) were 
manufactured to submerge the net more satisfac¬ 
torily in a seaway, and favorable trial reports were 
obtained on at least two. 6 

It had been noted that the Blondin roller used 
with the nets often failed as a result of abrasion and 
direct loading. In place of the small-diameter, cast- 
iron rollers, malleable iron rollers were substituted 
and gave better service. These new rollers should 
have been even larger in diameter, but the circum¬ 
stances of the investigation did not permit this 
change. 6 

In order to obtain a mesh strand intersection clip 
which would not tear or slip at torpedo impact, a 
double-barreled steel sleeve was produced and 
swaged onto a strand intersection. It resisted slip 
and tear up to the breaking strength of the strand 
itself. 12 


<l See Summary Technical Report, Division 6, Volume 14, 
NDRC, in press. 















252 


TORPEDO PROTECTION FOR MERCHANT VESSELS 


UNDERWATER PHOTOGRAPHY 

In order to determine the exact manner in which 
TND nets operate and in which the mesh entangles 
the tail of a torpedo, consideration was given to the 
possibility of obtaining a series of underwater photo¬ 
graphs. 

Locations were found in southern waters where 
the water is about 45 to 50 feet deep with slow cur¬ 
rents and sufficient clarity to permit underwater 
photography. It was planned to place three high¬ 
speed cameras in each of two underwater caissons 
which could be supported from a stationary bridge 
and maneuvered out of the way if an off-target tor¬ 
pedo endangered them. The cameras would be oper¬ 
ated from the surface and would be focussed on a 
point about 15 feet away, covering an area approxi¬ 
mately 10 to 15 feet square. 

It was then planned that an EC-2 ship of heavy 
draft woidd travel at normal speed along a line of 
buoys so that her nets would pass through the area 
of camera focus, and that a firing device at a pre¬ 
scribed distance would discharge a torpedo to hit the 
net in the area in focus. 

It soon became apparent that the acquisition of a 


target ship arid a firing device, the construction of the 
camera supports, and the preparation of necessary air 
and surface protection would entail very consider¬ 
able expense and some hazard. It became apparent, 
too, that because of the limited accuracy of available 
torpedo-firing devices and because of the water tur¬ 
bulence in a torpedo wake, the chances of obtaining 
successful underwater photographs in the manner 
contemplated are practically nil. Accordingly, be¬ 
cause of the difficulties, expenses, and hazards in¬ 
volved, this phase of the project was not carried any 
further. 

Figure 20 shows frames selected from moving pic¬ 
tures made under water in a clear Florida lake with a 
brilliant sandy bottom. The pictures were taken of a 
propeller on a surface craft by means of special sub¬ 
surface equipment manufactured by the Bell Tele¬ 
phone Laboratories. 

It was suggested later that preliminary experi¬ 
ments lie made with a model torpedo and a model 
moving net, reduced to a 1 to 10 scale, in clear inland 
waters or a suitable tank, but this plan was not ap¬ 
proved because of the great expense of a model tor¬ 
pedo and moving net, and the length of time neces¬ 
sary to acquire the needed technique. 







Chapter 15 

LAND COMBAT VEHICLES 


Summary 

lans have been made for the development of a new 
series of combat vehicles designed to combine the 
best features of tanks already tested in battle with the 
best new features developed by collaboration of lead¬ 
ing military, scientific, and industrial authorities. 
This new “Turtle” series includes lightly armored 
but highly mobile units suitable for air transport, 
medium units, and heavy units. 

Mock-ups were prepared for the lust two types in 
the series. One of these, investigated only in an ex¬ 
ploratory study, is a medium tank with a weight of 
approximately 35 tons, a low silhouette, an all-welcled 
hull, and a 3-inch gun. Consideration was given to 
various modifications, including one with twin 37- 
mm guns, another with four .50-caliber machine 
guns, a heavy assault unit carrying an 81- or 105-mm 
gun, and a unit specially designed for defense against 
low-flying planes and carrying two eight-gun pom¬ 
pom type mounts. 

The second type, the light, highly mobile combat 
vehicle, was studied in two models—one with eight 
wheels to carry a 3-inch gun, the other with four 
wheels to carry lighter armament. Both models in¬ 
clude all-wheel drive, a hydraulic anti-recoil system, 
and a new type of independent, all-wheel suspension 
to enable the vehicle to jump over ditches, fences, and 
similar obstacles. The design of these models is fea¬ 
tured particularly by the large energy absorption of 
the suspension to give improved riding qualities, 
large recoil-absorbing capacity even with conven¬ 
tional type shock absorption, brake-balanced differ¬ 
ential drive, and provision of facilities enabling the 
vehicle to squat. A full-scale test unit consisting of 
one wheel with its drive, suspension, adjacent frame 
members, and hydraulic jumping equipment was 
constructed and submitted to tests. These indicated 
that a full-scale vehicle incorporating the newly de¬ 
veloped system can clear a height of 49 inches and a 
length of 47 feet at a speed of 40 miles per hour. 

Because of inability to secure the cooperation of 
the Chief of the U. S. Army Ordnance Department 
and the automotive industry, all work on the Na¬ 
tional Defense Research Committee [NDRC] series 
of tanks was abandoned. 


in another study, preliminary plans were prepared 
for vehicles, devices, and techniques for use in demol¬ 
ishing enemy-held public utilities systems and later 
in restoring them. 

o 

i5i TURTLE 1 

1511 The Problem 

In April 1941, after observations on the perform¬ 
ance of current tanks and particularly after a study 
of their resistance to enemy attack, it appeared to 
both NDRC and the Ordnance Department that im¬ 
provement was necessary in the design of gun mounts, 
vision devices, ammunition feed systems, and in the 
means for operating the turrets. 

Although work was undertaken on improving 
these tank components, as reported later in this 
chapter, it soon became apparent that any major 
improvements were limited by the over-all design 
of American tanks. Accordingly, a project was set up 
for the design, construction, and testing of one or 
more full-scale pilot models of a series of armored 
combat vehicles. These vehicles were to incorporate 
those characteristics found most desirable in battle, 
together with the most useful new components which 
could be developed in cooperation by military, sci¬ 
entific, and industrial authorities. 

Later, after major tank engagements in Russia and 
the Libyan desert had disclosed many of the actual 
advantages and weaknesses of our tanks and other 
armored vehicles in modern battle, this broad re¬ 
search and development program was given addi¬ 
tional though temporary impetus by a formal 
directive from the Chief of Army Ordnance. 

In general, the specifications called for combat ve¬ 
hicles which would have maximum superiority over 
enemy vehicles and maximum protection against 
enemy antitank techniques. They included (1) a high 
degree of mobility, (2) a stable firing platform, (3) 
high firing accuracy while in motion, (4) a low silhou¬ 
ette and silent operation for security and surprise, (5) 
complete integration of functions of each type to per¬ 
mit either independent or group operation, and (6) a 


a Projects OD-30 and OD-60. 





253 




254 


LAND COMBAT VEHICLES 


high degree of mechanical reliability. It was agreed 
that each type in the series should lend itself to mass 
production by incorporating as far as possible those 
components which were already available, and that 
the synthesis of these components into a complete, 
efficient vehicle should not require prolonged devel¬ 
opment or mark any departure from proved engineer¬ 
ing principles. 

151 2 IVI Tank b 

Procedure 

An analysis of medium tank design led to a number 
of fundamentals which were considered desirable for 
attainment of the major objectives. 0 These were: 

1. Ninety per cent of all tanks should have the 
same chassis, making mass production possible. 

2. Ninety per cent of all tanks should have the 
same standard, adequate armor for their vital parts 
and for their crews. 

3. Ninety per cent of all tanks should have weap¬ 
ons capable of both offensive and defensive action 
against other tanks, antitank guns, pill-boxes, in¬ 
fantry, and low-flying aircraft. 

1) Project OD-30. 

c This investigation was conducted by the United Shoe Ma¬ 
chinery Corporation, Boston, Mass. 



Figure 1. Model of IVI-C medium tank equipped with 
75-mm gun. 



Figure 2. Model of IVI-C medium tank equipped with 
two 37-mm guns. 


4. All tanks should have interchangeable and re¬ 
placeable armament which could be applied without 
redesigning the tanks or making major changes either 
on the production line or in the field. 

5. Ninety per cent of all tanks should carry weap¬ 
ons with a rate of fire at least equal to that of a hand- 
operated, full-crew gun of equal caliber—a require¬ 
ment which can be met only by automatic weapons. 

6. Weight should be reduced to a minimum to 
give high speed. 

The turret in the tanks existing at the time of this 
study was deemed incapable of providing the protec¬ 
tion expected of it, and its added weight did not seem 
to be justifiable. T he small space within the turret 
prohibited full use of automatic weapons. Turret de¬ 
signs increased the complexity of tank production. 

Therefore, it was felt that the turret should be 
completely redesigned and arranged to incorporate 
such guns as the 75-mm gun with a rate of fire of 30 
to 45 rounds per minute, the M-4 37-mm gun with a 
rate of 120 rounds per minute, or the .50-caliber ma¬ 
chine gun with automatically operated remote con¬ 
trols. The 75-mm gun was then being redesigned, the 
37-mm gun was in production for the P-39 Airacobra 
fighter plane, and the .50-caliber machine gun was 
ready to go into production for the Army Air Forces. 

With such guns as these, it was believed that the 
chassis and transportation portion of the tank could 
be mass-produced, and that the armament could be 
installed without difficulty to give any desired fire 
power combination. 

Mock-ups were prepared in this exploratory study 
to show the possibilities of a basic chassis and protec¬ 
tive armor, low silhouette, and interchangeable and 
readily replaceable automatic fire power. 

Results 

Design IVI-C. One concept of the new medium 
tank design represents a more or less conventional 



Figure 3. Model of IVI-C medium tank equipped with 
four .50-caliber machine guns. 








TURTLE 


255 


organization, drive, crew, and armament. The crew 
is reduced to four men, a driver and a radio operator 
forward of the turret, a commander and a gunner in 
the turret. This tank would weigh 30 to 35 tons and 
would be 7 feet high, 9 feet 4 inches wide, and 18 
feet 7 inches long. 

The main turret armament consists of one 75-mm 
cannon, two 37-mm cannons, or four .50-caliber ma¬ 
chine guns, all of them replaceable and interchange¬ 
able (Figures 1 to 3). These guns are capable of 
360-degree rotation in azimuth, and elevations of 
— 10 to +45 degrees for the 75-mm, and —10 to +85 
degrees for the 37-mm and the .50-caliber. In addi¬ 
tion, the driver has two .30-caliber machine guns 
capable of —10 to +30 degrees elevation, and the 
commander, located in the turret, has one forward 
.30-caliber machine gun for fire against ground 
troops and low-flying aircraft and one rear .50-caliber 
machine gun. 

The armor is from 3 to 31+ inches over all vulner¬ 
able surfaces and can continue down over the treads 
to the road clearance (16 inches). The low surface 
angles and the small frontal and side areas exposed 
to lire should offer considerable protection against 
enemy fire. In this particular design, the crew are 
well below the main body lines of the tank and are 
well protected. 

Automatic feed is planned for all armament to 
give maximum rate of fire. Accuracy of fire would be 
improved by stabilization of the gun in both azimuth 
and elevation, and possibly by stabilization in eleva¬ 
tion and azimuth of both gun and driver through 
some limited throw such as 10 degrees. 

The gunner has 360-degree azimuth vision afforded 
by the turret rotation. His elevation vision depends 



Figure 4. Model of IVI-D medium tank equipped with 
75-mm gun. 


upon the main armament used. The commander 
has 360-degree azimuth vision independent of the 
turret and -10-degree to +85-degree elevation vi¬ 
sion. The driver has -10- to +30-degree elevation 
and no azimuth vision. 

By use of a 600-lip motor and by the reduction of 
track friction, a speed of 30 to 35 miles per hour is 
believed possible. Air-cleaning and air-conditioning 
equipment coidd be included for certain services in 
order to maintain the efficiency of the crew and the 
life of the mechanical parts. 

The tank would be designed for mass production 
using large unit pieces rather than assemblies which 
would require accurate fits and prolonged assembling 
operations. 

In contrast to the M-3 medium tank, the IVI-C 
has a low, compact design with minimum crew re¬ 
quirements and sufficient volume to carry necessary 
auxiliary equipment and gasoline for a greater op¬ 
erating range. Its silhouette is 3 feet lower. It woidd 
be capable of resisting heavy caliber fire because of its 
heavier armor and low deflection angles. The total 
weight of the IVI-C, however, would be greater be- 



Figure 5. Model of IVI-D medium tank equipped with 
two 37-mm guns. 



Figure 6. Model of IVI-D medium tank equipped with 
four .50-caliber machine guns. 











256 


LAND COMBAT VEHICLES 


cause of its increased armor thickness and the use of 
armor over the treads. 

Design IVI-D. This design is the same as that for 
the IVI-C series except that the turret enables the 
gunner to move with the gun both in azimuth and in 
elevation (Figures 4 to 6). Such a modification pro¬ 
vides the most direct solution of the problem of high- 
angle vision, for the vision device is a straight-through 
protectoscope similar to that used in the M-3 medium 
tank. The field of such a protectoscope could be con¬ 
siderably greater than for the type in use, since it 
need not be contained in a small drum. 

I he elevation lor this type of gun mounting can be 
increased to +85 degrees without increasing the over¬ 
all height of the tank. 4’he design also allows the use 
of low surface angles on the sides of the turret. 

Certain disadvantages, however, are apparent. This 
type of turret requires more machining, difficult 
shielding is recptirecl to protect adjoining sliding- 
surfaces from shellfire, and more armor is needed in 
the areas of the rotating portion which are vulner¬ 
able to shellfire throughout the entire elevation of 
the gun. 



Figure 7. External view of model of modified IVI me¬ 
dium tank. 



Figure 9. Model of proposed assault unit to be equipped 
with 81- or 105-mm gun. 


Special Designs. Figures 7 and 8 show a slightly 
different arrangement of operator, motor, and guns. 
Use of this modification would depend on a careful 
consideration of cubage, operator comfort, gun op¬ 
eration, etc. 

The mock-up of an assault unit is shown in Figure 
9. This is a shielded, heavy-caliber mount for an 81- 
or possibly a 105-mm gun, and would have the major 
purpose of assaulting enemy strongholds, such as 
pillboxes and fixed fortifications. In addition it 
would carry a gun crew and selected shock troops 
to aid in holding positions taken. 

An antiaircraft unit, illustrated in Figure 10, is 
designed for defense against low-flying aircraft. With 
two eight-gun pom-pom type mounts, it would direct 
heavy fire against hedge-hopping planes attempting 
to bomb or strafe troops, and would have sufficient 
speed and mobility to keep up with the advance 
ground forces. 4 



Figure 8. Internal view of model of modified IVI medium 
tank. 



Figure 10. Model of IVI antiaircraft unit equipped with 
two eight-gun, pom-pom type mounts. 







TURTLE 


257 



Figure 11. Model of eight-wheel light combat vehicle. 


15,1-3 Baker Tank' 1 

Procedure 

In the development of light units to be included 
in the proposed Turtle series, it appeared that the 
program could be most profitably started by the de¬ 
sign for a new type of combat vehicle—a self-propelled 
assault gun to take a leading role against tank, anti¬ 
tank, and artillery gun emplacements. It would com¬ 
bine many of the best features of the long-range 
reconnaissance car and the tank destroyer, represent¬ 
ing a transition in offensive weapons. 

As outlined by NDRC, the first step in this project 
was the selection of a gun which would be satisfac¬ 
tory to the Ordnance Department. Once the major 
armament was approved, design work could begin on 
the most efficient chassis to carry it, the best method 
of applying traction, the best armor to protect it, and 
the best tactical aids which could be taken from cur¬ 
rent armored vehicle models, developed by other 
NDRC projects already under way, or designed in 
new NDRC projects to be set up for that purpose. 

Armament. Immediate consideration was given to 
both high-velocity and hyper-velocity guns which 
were either available or undergoing final develop¬ 
ment, together with special projectiles developed 
for some of them. 


d Project OD-60. 


Among the high-velocity guns studied were the 
twin 37-mm guns used in the Maxson turret, the 57- 
nim gun for light tanks, the 75-mm gun with an in¬ 
creased muzzle velocity of 2,600 fps, the 88-mm gun 
for 25-ton tanks, the 90-mm antiaircraft gun, and the 
British 3-inch gun. Of these, the 3-inch gun appeared 
to be the most useful. It weighs only 2,650 pounds 
with its mount,-in contrast to 5,000 for the 90-mm 
gun, and, with a muzzle velocity of 3,000 feet per sec¬ 
ond, will penetrate 90-plate steel at 1,600 yards. This 
gun has a useful destructive range of 3,000 yards and 
a maximum range of 8,000 yards; it can fire 2,500 
rounds at 2,650 fps and 500 at 3,000 fps. 

Consideration was likewise given to hyper-velocity 
guns, which were developed to minimize erosion, 
particularly at the breech end of the tube where it 
reduces the life of the gun, and to give a higher 
muzzle velocity, a flatter projectile trajectory, a short¬ 
er time in flight, and a higher penetration of armor. 
Of all the hyper-velocity devices available or under 
development, 3 ’ 7 the best for the purpose appeared 
to be the Probert gun, at the time being proved in 
England, which develops muzzle velocities of 3,300 
to 3,500 fps; the Janacek choke and the Littlejohn- 
Janacek conversion, which fit over the muzzle of a 
standard gun and adapt it to the conical bore princi¬ 
ple; and the modified Kern and Gerlich conical bore 
guns which were then being studied by other divi- 















258 


LAND COMBAT VEHICLES 



Figure 12. Model of four-wheel light combat vehicle, with turret removed. 


sionsof NDRC. At the same time, attention was given 
to the Arrowhead-type projectiles being developed 
by the British and the U. S. Army, which develop a 
muzzle velocity of more than 4,200 fps, and to deform¬ 
able projectiles under consideration by the British 
and the U. S. Navy. Although interest was constantly 
maintained in all these types, none appeared to be 
sufficiently developed or satisfactory for incorpora¬ 
tion in the proposed new combat vehicle. 

Accordingly, the preliminary designs were under¬ 
taken for a combat vehicle to carry the British 3-inch 
gun as its major armament. 

Chassis. As a result of improvements in armor-pierc- 



Figure 13. Extent of suspension travel shown in model of 
four-wheel light combat vehicle. 


ing weapons, it seemed desirable to design the new 
vehicle as a lightly armored but highly mobile tank 
which would offer relatively little protection against 



Figure 14. Interior layout of model of four-wheel light 
combat vehicle. 














TURTLE 


259 


direct artillery fire but which would be exceedingly 
difficult to hit. To provide this mobility over any 
kind of terrain and to reduce maintenance require- 
ments, it was decided to use wheels instead of tracks, 
with all wheels driven, and to make provisions for 
air transport. 6 


Early in the program, an investigation was con¬ 
ducted on the possibilities of incorporating some 
means to enable the vehicle to negotiate ditches, 
trenches, low fences, and similar obstacles by jump- 

6 This investigation was conducted by the Baker Manufactur¬ 
ing Co., Evansville, Wis., under OSRD contract OEMsr-524. 





Figure 15. Plan, front and side views of light combat vehicle as attached for air transportation. 






















































































LAND COMBAT VEHICLES 


260 



Figure 16. Jumping cycle: (1) chassis squats, (2) chassis accelerated upward, (3) wheels accelerated upward, (4) vehicle 
in air, (5) chassis decelerated upward, and (6) chassis rises to normal road clearance. 


ing over them. It was determined 5 that the vehicle 
could be made to jump by a sudden downward push 
of the running gear, and that the height and length 
of the jump would be determined by the length of the 
running gear downstroke, the magnitude of the 
downward force, and the forward velocity of the 
vehicle at the time of the jump. The apparatus re¬ 
quired for such a performance would consist of 
hydraulic or pneumatic cylinders, together with ap¬ 
propriate valves, an accumulator, and a pump driven 
from an engine. A rough plan was accordingly de¬ 
veloped for a mechanism to incorporate these units, 


a jumping technique was outlined, and a test unit 
was constructed for testing and analysis. 

In considering the possibilities of a jumping vehi¬ 
cle and also in reviewing existing wheeled vehicle 
designs, it was concluded that both the permissible 
travel of the spring suspension and the vehicle width 
should be as large as possible. The general design of 
the chassis therefore included maximum suspension 
travel in order to increase the resistance to shocks, 
including gun recoil reaction, to permit jumping, 
and to permit setting the bottom of the vehicle on the 
ground quickly to reduce recoil reaction movement 



Figure 17. Diagram of proposed hydraulic jumping system. 
































































































































































TURTLE 


261 



























































































































































































































































SECTION THROUGH 
THIS SIDE 


LAND COMBAT VEHICLES 


2f>2 






VM U /KU 





fr i / 



l • 





v 

C/D 

C/D 


be 




C/5 


O 



C/2 


C/D 

• »■ 
o 
u 


be 

r“ 








u 


C/D 

— 

u 


Cl 










































































































































































































































































































TURTLE 


263 


and to lower the silhouette. The width was made 
as great as possible to improve absorption of gun re¬ 
coil, to permit larger suspension, and to make possi¬ 
ble the use of a lower spring rate, giving a better ride 
for a given side roll in turning. 

Considerable improvement in traction was ex¬ 
pected by connecting an extra hydraulic system into 
the conventional hydraulic brake control in order to 
give automatic balancing of the drive differential. 

An investigation was also conducted on methods 
of minimizing the effects of gun recoil. Gyroscopic 
devices were studied as possible anti-recoil systems 
but discarded because of their undue size and com¬ 
plicated mechanisms. A system transmitting the 
torcpie through the wheels was considered prefera¬ 
ble, with the transmission accomplished most con¬ 
veniently by means of a hydraulic cylinder, and a 
workable design was investigated. 

Development studies and recommendations on 
other devices and improvements, including those 
concerned with reduction of tank noise, improve¬ 
ment of vision, gun mounts, communications, fire 
control, detection, navigation, camouflage, and vari¬ 
ous attack aids were conducted in cooperation with 
those Office of Scientific Research and Development 
and NDRC divisions concerned. 

Results 

Figure 11 shows a mock-up of the proposed eight- 
wheel vehicle, with a wheel base of 189 inches and a 
width of 121 inches. Its total weight, including two 
engines and a 3-inch or similar gun, is estimated to 
be less than 20,000 pounds. Figure 12 shows the 



Figure 20. Experimental wheel unit in normal position. 


chassis of a four-wheeled version to carry a smaller 
gun of about 40-nnn caliber, with a wheel base of 137 
inches, a width of 121 inches, and an estimated weight 
of less than 10,000 pounds. 17 

Both vehicles include all-wheel, brake-balanced 
drive, and the new type of independent, all-wheel 
suspension. Figure 13 shows one wheel in its highest 
position and one wheel in its lowest to illustrate the 
extent of the suspension travel. The interior layout is 
indicated in Figure 14, with facilities permitting the 
driver to steer in either direction from the same steer¬ 
ing wheel. 

Air Transport. Figure 15 shows the features of a 
scheme for transporting the vehicle by air in such a 
way that it can be quickly unloaded by releasing on 
touching or approaching the ground. It is believed 
that two 700-horsepower motors, a wing span of 124 
feet, and an over-all length of 66.5 feet would be re¬ 
quired. Maximum speed would be 145 mph, cruising 
speed 130 mph, and landing speed 50 mph. This plan 
would not be adapted for long-haul or high-speed air 
travel because of the low landing speed required and 
the large aerodynamic drag of the exposed vehicle. 

Jumping System. Theoretical studies and prelimi¬ 
nary tests on a device which would enable the vehicle 
to jump over obstacles led to the design of hydraulic 



Figure 21. Experimental wheel unit, chassis raised. 











LAND COMBAT VEHICLES 



2C>4 


Figure 22. Experimental wheel unit, chassis lowered. 


Figure 23. Merry-go-round setup for experimental wheel 
unit tests. 


Figure 24. Experimental wheel unit clearing height of 
49 inches. 


equipment which would operate in a six-step jump¬ 
ing cycle (Figure 16): 13 

1. A relatively slow squatting of the chassis to the 
minimum road clearance permitted by the terrain. 

2. A rapid upward acceleration of the chassis with 
respect to the wheels by means of hydraulic cylinders. 

3. A rapid acceleration of the wheels up to the 
velocity of the chassis, accomplished by a throttling 
buffer at the end of the hydraulic cylinder. 

4. A flight through the air during which the vehicle 
would hurtle the obstacle. 

5. An upward deceleration of the chassis, during 
which the kinetic energy of vertical velocity of the 
chassis would be absorbed. 

6. A relatively slow raising of the chassis up to 
normal road clearance. 

During step 4, the wheels could be raised and the 
net height of the jump would be increased, but the 


added operations of raising and then lowering the 
wheels would require the use of twice the oil ex¬ 
pended in step 3 and would necessitate more com¬ 
plicated apparatus. 

In the proposed jumping system as shown in Figure 
17. the energy for jumping is supplied to an oil pump 
and is stored by compressed air in power accumu¬ 
lators from which it is transmitted hydraulically to 
the jumping cylinders. 15 In order to investigate the 
actual operation of such a system, a full-scale wheel 
unit with drive, suspension, and adjacent frame mem¬ 
bers was constructed as shown in Figure 18, with the 
hydraulic cylinder used for jumping and for absorb¬ 
ing shocks, as shown in Figure 19. Oil enters the 
cylinder on the top trunnion axis, making a right- 
angled turn just at the cylinder entrance. Oil leaving 
the lower side of the cylinder flows through the an¬ 
nular space surrounding the cylinder and out along 
the trunnion axis. The suspension and cushions are 
provided hydraulically by means of piston extensions 
which restrict the flow of exit oil near the ends of the 
stroke. 

Figure 20 shows the experimental unit, Figure 21 



















TURTLE 


265 



Figure 25. Sequence of views showing experimental wheel unit during jumping (left to right). 


illustrates the highest suspension position, and Fig¬ 
ure 22 shows the lowest position. 

This unit was then mounted on a large radius arm 
to permit merry-go-round testing, as shown in Figure 
23. File tests showed that the basis of the design is 
fundamentally sound. In one jump, as illustrated 
in Figure 24, the wheel cleared a height slightly more 
than 49 inches; for a vehicle with a 137-inch wheel 
base traveling at 40 mph, this height corresponds to 
a jumping distance of 47 feet. 

A series of moving picture views of the suspension 
during jumping is shown in Figure 25. 19 

Anti-Recoil System. The equipment required for 
a possible hydraulic anti-recoil system for the Turtle 
is illustrated in Figure 26. 11 The source of pressure is 
connected to both ends of each cylinder through 
valves sensitive to vertical accelerations. The valves 
connected to the lower ends of the cylinders admit 
pressure proportional to acceleration into the lower 
hah es of them when the valves are accelerated down¬ 
ward. An upward force is thereby produced similar 
to that which would be exerted by an added mass. 
The action of the valves connected to the upper ends 
during upward acceleration is similar. Fixed orifices 
are located between the acceleration-controlled valves 
and the cylinders. These orifices add to the pressure 
in the end of each cylinder from which oil is being 


forced out and subtract from the pressure in the end 
into which oil is being admitted, producing a force 
which is a function of the relative velocity between 
the chassis and the wheels. 

One possible type of acceleration-controlled valve 
is shown in Figure 27. When the pressure in the inlet 
pipe is too low; the plunger is pushed to the left, 
either increasing the opening of an orifice from the 
source of pressure or decreasing the opening of an 
orifice leading to the sump, thereby increasing the 
pressure in the inlet pipe. When the pressure is too 
high, the action is similar except that the movement 
takes place in the opposite direction. Thus the pres¬ 
sure in the inlet pipe is maintained approximately 
proportional to the acceleration. When downward 
accelerations occur, the mass opens wide the outlet 
valve of chamber C and the pressure in C falls, caus¬ 
ing the valve between the inlet pipe and the sump 
to open completely. 

During recoil, the acceleration-controlled valve 
can operate without a source of pressure and acts as 
an added mass, while during the continued rocking 
in the same direction after recoil, the valve cannot 
operate and the added mass disappears. 

A valve such as the one in Figure 28 is required at 
each end of each cylinder. This is similar to the one 
in Figure 27 except that the oil flowing into chamber 










266 


LAND COMBAT VEHICLES 


C comes from a space between the throttling valve 
and a pop-off valve. The pop-off valve maintains an 
approximately constant pressure while oil is flowing 
through it. 

Miscellaneous. Many of the devices and develop¬ 
ments studied by various divisions of NDRC are be¬ 
lieved to be more or less applicable to these and other 
vehicles. Studies on the reduction of tank noise, cen- 



Figure 26. Diagram of proposed hydraulic anti-recoil 
system. 


trifugal self-cleaning air cleaners, gun mounts, view¬ 
ing devices, protectoscopes, gunner’s seats, bouncing 
characteristics, and control of fog, sleet, and rain are 
reported elsewhere in this volume. The reports on 
ordnance improvements, fire control, automatic feed, 
improved armor, tank rockets, special hydraulic 
fluids, flame throwers, special communications sys¬ 
tems, mine detectors, odographs, and the use of radar, 
infrared, and ultraviolet devices on tanks—all orig¬ 
inally contemplated for the vehicles described above 
—are included in the summary reports of other divi¬ 
sions. 

Conclusions 

To a large extent, the directive for this project was 
not fulfilled, for no complete pilot model was con¬ 
structed and subjected to test. Nevertheless, the de¬ 
sign and the principles developed for combat vehicles 
are believed to be noteworthy and warrant investiga¬ 
tion on full-scale models in field trials. 


CONTROL MASS 



Figure 27. Diagram of acceleration-controlled valve. 

CONTROL MASS 



Figure 28. Diagram of modified acceleration-controlled 
valve. 


15 -2 DEMOLITION VEHICLE f 

In the autumn of 1941, Division 12 of NDRC gave 
some consideration to the development of techniques, 
devices, and a necessary vehicle to be used in the 
demolition of enemy public utility facilities. It was 
suggested that this equipment might be used by 
highly trained specialists to destroy such services as 
power, light, heat, telephone, telegraph, radio, water, 
and sewage disposal systems in enemy cities. 

This program was formally requested by the U. S. 
Army in September 1941 with a directive from the 
Executive Officer, Corps of Engineers, requesting 
recommendations of techniques and equipment to 
prevent enemy operation of such services as power, 
water, and communications. At the same time, the re¬ 
quest called for the development of restoration tech¬ 
niques which could be applied by troops upon 
occupying enemy territory. 

After preliminary plans had been outlined, the 
project was terminated by request of NDRC on the 
grounds that any techniques or devices developed in 
this study might imperil public utility facilities in 
this country and increase the dangers of sabotaged 


f Project CE-20. 

s Secret letter from Frank R. Jewett, NDRC. to General G. M. 
Barnes, War Department Liaison Officer, NDRC. Washington, 
D. C., Dec. 3, 1941. 


e a r ~ 


















































































































Chapter 16 

LAND VEHICLE COMPONENTS 


16 1 TANK COMPONENTS 

Summary 

A n urgent development program undertaken at 
^ the request of the U. S. Army Ordnance Depart¬ 
ment in April 1941 resulted in the design of new gun 
mounts, viewing devices, protectoscopes, and other 
tank components, and a self-cleaning centrifugal air 
cleaner for use on tanks and other motor vehicles. 
None of these items was put into production. 

1611 The Problem 

Battle reports from Europe and Africa before the 
United States entered World War II indicated that 
American tanks suffered from such defects as poor 
visibility, vulnerability to small-arms fire by lead 
splash, poor functional posture for the gunner, and 
restricted elevation of gun mounts. 

At the request of the U. S. Army Ordnance Depart¬ 
ment and the National Defense Research Committee 
[NI)RC], an urgent development program was un¬ 
dertaken in April 1941 to obtain new gun mounts, 
viewing devices, protectoscopes, and other tank com¬ 
ponents. b The program was to be directed primarily 
toward devices to be used on the experimental T-7 
light tank, but also concerned the M-4 medium tank. 2 

Soon after the introduction of motor vehicles to 
desert warfare, a drastic increase in failure reports 
marked the urgent need for a self-cleaning device to 
clean the air intakes of tank and truck engines. The 
oil-filter type of cleaner had not proved satisfactory, 
requiring a thorough cleaning itself after a few hours 
of exposure to desert dust. Tanks, trucks, and even 
aircraft exposed to this atmosphere were failing in 
such numbers that the Allied desert military cam¬ 
paign was gravely affected. So alarming was the situa¬ 
tion that one military observer urged the Chief of 
Army Ordnance and Division 12 of NDRC, “Design 
a proper air cleaner, and then design a tank around 
it!” 


« Project OD-30. 

b This investigation was undertaken by the United Shoe Ma¬ 
chinery Corporation, Boston, Mass., under contract NDCrc-204 
and OSRD contract OEMsr-112. 


161,2 Gun Mounts 

In order to increase protection for tanks against 
aircraft attack, new gun mounts were required for 
the turrets of light and medium tanks. In the specifi¬ 
cations set up and approved by representatives of the 
U. S. Army Ordnance Department, these mounts 
should make it possible to cover elevations up to 80 
or 90 degrees. They should be mechanically simple, 
easy to machine, statically balanced, and interchange¬ 
able with other mounts. They must have a minimum 
of exposed surfaces, no pockets or re-entrant angles, 
a minimum spatter lap of 2 inches, and means to 
catch spatter that does get through, deflectors in line 
of probable fire, and sufficient clearance to avoid 
sticking of the rotor. 

Combination High-Angle Mount and 
Protectoscope 

The original request initiating work on tank prob¬ 
lems involved redesigning a combination 37-mm, 
.30-caliber gun mount to permit greater gun eleva¬ 
tion (up to 80 or 90 degrees), as well as relocating and 
redesigning the associated protectoscope. The new 



Figure 1. Mock-up of high-angle mount with gun fully 
elevated. 





268 


LAND VEHICLE COMPONENTS 


design was originally intended for the M-4 medium 
tank, but later was considered for the T-7 light tank 
turret. 

Figure 1 shows the features of the first design. The 
wall of the front plate around the gun opening is 
built up with flanges to aid in protecting the rotor 
from side fire and lead splash. At full gun elevation, 
two shields, as shown in Figure 2, attached to the gun 
rotor protect the rotor by overlapping the Hanged 
side walls. The shield is divided into two parts, a 
fixed part attached directly to the gun rotor and a 
movable part hinged to the fixed part. At low eleva¬ 
tions this hinged shield cams outwardly on a fixed 


member to prevent interference with the turret shell 
and basket. 

With this design, the guns can fire at an angle of 
85 degrees. 

In order to provide better protection to the rotor, 
smoother contour, and fewer pockets, the structure 
was changed and a redesigned recoil mechanism was 
placed completely inside the rotor (Figure 3). In this 
plan, the rotor diameter is increased and the hinged 
shields replaced by a single fixed shield. This design 
gives good protection only at the most commonly 
used firing elevations. 

The redesigned protectoscope is described below. 



FIXED MEMBER 




-MOVABLE SHIELD 


FLANGES 


FIXED SHIELD 


Figure 2. Mock-up of high-angle mount with gun lowered. 



Figure 3. Mock-up of modified high-angle mount with 
single fixed shield. 


FIXED FRONT 

SHIELD PLATE 



PROTECTOSCOPE 


Combination Low-Angle Mount and 
Protectoscope 

In designing the high-angle gun mount, it was 
found quite difficult to obtain satisfactory protection 
for the gun rotor over the wide range of gun eleva¬ 
tions, and a low-angle mount was developed to give 
elevations between —10 and +25 degrees. This model 
(Figures 4 and 5) provides complete protection of the 
rotor from machine gun fire by the use of a shield 
fixed to the rotor. In order that the shield may clear 
the turret shell and basket, the rotor diameter is 
increased and the front plate is completely rede¬ 
signed. The new recoil mechanism, completely 
housed within the rotor, is incorporated. 

Adequate vision is made possible by means of a 
protectoscope with a rotatable upper mirror. A mir¬ 
ror rotor and mirror magazine are connected to the 



MIRROR MAGAZINE SHAFT GEARS GUN 

ROTOR 




MAGAZINE 


FEED 


Fig ure 4. Outside view of mock-up of low-angle mount. 


Figure 5. Inside view of mock-up of low-angle mount. 










TANK COMPONENTS 


269 


gun rotor by means of links, a shaft, and a train of 
gears, and move in proper angular relation to the 
gun. Without moving his head, the operator can aim 
the gun through a special sighting telescope in con¬ 
junction with the protectoscope at any elevation 
within its range. Upper mirrors are replaceable 
through a slot from a magazine (see the description 
of M-4 protectoscope below). If the mirror rotor or 
magazine should be damaged, a spare indirect vision 
device can be slipped into place. The gunner is pro¬ 
tected from lead spatter by lap joints, spatter traps, 
and safety glass. 

Rear Turret Machine Gun Mount and 
Protectoscope 

In addition to the combination mounts, a request 
was also made for a mount to carry a single .30-caliber 
machine gun and protectoscope in the rear of the T-7 
light tank turret. Since the gun was to provide pro¬ 
tection against aircraft, a high elevation range was 
specified. 

The mount as designed to meet these requirements 
consists of a rearward-pointing, .30-caliber machine 
gun capable of pivoting on both axes and with an 
elevation range of —10 to +85 degrees (Figures 6 and 
7). T he companion protectoscope is mounted on the 
gun trunnion and moves with it. A special cam ar¬ 
rangement between the upper and lower mirrors 
gives them different angular movements which per¬ 
mit the gunner to sight through the entire elevation 
range with a minimum of head movement. Azimuth 
sighting is limited to 50 degrees by the width of the 
mirrors. 



Figure 6. Outside view of model of rear turret machine 
gun mount. 


Multiple Machine Gun Mount 

At the request of the Ordnance Department, a 
study was also started on the design of a multiple 
.50-caliber machine gun mount with an elevation 
range of —10 to +85 degrees for the M-4 medium 
tank. Layout and design drawings were completed 
but construction of a model stopped upon abandon¬ 
ment of the project by the Army. 

16.1.3 Panoramic Observation Devices 

A need was expressed by Ordnance Department 
representatives for devices which would make possi¬ 
ble 360-degree vision for panoramic observation from 
tank turrets. Three different designs were prepared. 

Direct Vision Device 

This simplest solution for application to the T-7 
light tank turret provides a crank, chain drive, and 
sprockets to rotate screws which in turn can raise or 
lower the turret cover (see Figures 6 and 7). When the 
cover is raised, the gunner can make his observations 
through a 360-degree slot. 

Hexagonal Low-Angle Viewer 

A more complex and safer device was designed for 
use on either the T-7 light tank or the M-4 medium 
tank turret (Figure 8). The main rubber-lined body 



PROTECTOSCOPE 

8pHI . 


COVER 


GUN TRUNION 


Figure 7. Inside view of model of rear turret machine 
gun mount. 














270 


LAND VEHICLE COMPONENTS 


has six slots placed 60 degrees apart in the plane 
view. In each slot is a replaceable unit periscope con¬ 
sisting of an upper mirror and a lower sheet metal 
mirror. The periscopes are replaceable from the in¬ 
side. Since the six individual fields overlap, the ob¬ 
server can see the full field in all directions by simply 
turning his head. He is protected from lead splatter 
by special “buckets” and safety glass. The device has 
a very low silhouette above the turret roof and is 
designed for bullet deflection. 

Adjustable High-Angle Viewer 

A further improvement on the low-angle device 
was designed to enable the observer to vary his field 
of vision in elevation from —10 to +70 degrees (Fig¬ 
ure 9). Here the upper mirrors are cam-operated to 
give the desired angle. Other features of construction 
are similar to those of the low-angle viewer. 


161-4 Protectoscope 

Fhe original specifications for a new tank turret 
protectoscope, as set up and approved by representa¬ 
tives of the U. S. Army Ordnance Department and 
NDRC, called for a small, simple, wide-angle view¬ 
ing device which would give the operator maximum 
protection while using it or while replacing any of 
its exposed parts which might be damaged by gun¬ 
fire. 

Its horizontal field of vision should be 25 degrees 
on each side of center, or a total of 50 degrees, its ver¬ 
tical field 11 degrees, and it should be able to cover 
an elevation of —15 to +90 degrees or at least to the 
limits of the gun elevation. Where possible, plane 
mirrors should be used. 

In addition, the new protectoscope must contain a 
sighting telescope on one side and provide means 
for coordinating with the gun. Provisions must be 
made for enabling the operator to steady his head 


UPPER MIRRORS 



while sighting, to keep his eye a fixed distance from 
the telescope, and, if possible, to get emergency vision 
in case the optical system fails. There must be a mini¬ 
mum of exposed surface, with no moving parts of the 
optical system in line of fire, a minimum spatter lap 
of 2 inches and means to catch spatter that does get 
through, and sufficient clearance to avoid sticking 
when pitted. The dimensions called for a maximum 
diameter of 12 inches, prelerably 5, and an over-all 
scope width of 8 inche . If possible, the protectoscope 
should be interchangeable in all mounts. 

Essentially, the requirements demanded an ex¬ 
ceedingly close-coupled periscope with the smallest 
number of exposed parts and with facilities for the 
operator to replace any of these exposed parts with¬ 
out exposing himself to enemy fire. 

M-4 Protectoscope 

File device as developed originally for the M-4 
medium tank and later for the T-7 light tank is de¬ 
signed as a periscope using a rotatable upper mirror 
(Figure 10). Eh is mirror is connected by gears, links, 
and shafts (Figure 11) to the gun rotor and turns in 
such relation to the gun that the gunner always sees 
the field at which the gun is aimed. 

If the mirror is shot away, it is replaced with a new 
one taken from a mirror box and slipped into place 
by means of a magazine feed (Figure 12). T he maga¬ 
zine itself is mounted on the mirror rotor and feeds 
new mirrors through a protected slot in the rotor. 
One stroke of the handle moves the mirror halfway 
out, where a small stop drops in behind and holds 
the mirror. A second stroke of the handle then moves 
the mirror the rest of the way out and into grooves in 
the main rotor (Figure 13). After the mirror has been 
ejected from the magazine, a flat spring pushes a new 


UPPER MIRRORS 



Figure 8. Hexagonal low-angle viewer. 


Figure 9. Adjustable high-angle viewer. 








TANK COMPONENTS 


271 



Figure 10. Rotatable upper mirror for protectoscopc. 


mirror into position in the magazine, reach to be led 
through the slot. 

A headrest is provided so that the operator can 
steady his head at a fixed distance while sighting. 

A model of this device was constructed of cast- 
armor steel and tested against .30-caliber Army rifle 
and .50-caliber machine gun fire. The protectoscopc 
satisfactorily sustained hits from both ball-type and 
armor-piercing bullets except when they struck di¬ 
rectly on the small rotors carrying the mirror and 
mirror magazine. The magazine principle of mirror 
ejection, however, proved successful. No lead splash 
penetrated to the operator’s position. 

161,5 Machine Gun Accessories 

In order to improve the firing of the .50-caliber 
Browning machine gun manufactured by Colt for 
the M-4 medium tank, a study was conducted of an 
electrically powered assist-feed to lift belts of cart¬ 
ridges from the rounds container and deliver them 
to the gun as fast as needed. At the request of repre¬ 
sentatives of the Ordnance Department, the device 
was to fit the standard Browning gun without requir¬ 
ing changes in the gun proper. 

M-4 .50-Caliber Machine Gun Assist-Feed 

"Fhe assist-feed as shown in Figures 14 and 15 con¬ 
tains as a power source a 110-volt a-c stalling motor, 
power-drill type, working through a torsion spring 
which drives a sprocket. This sprocket pulls the belt 
through rolls which give it a quarter turn to line up 
the cartridges from the rounds container with the 
gun axis. Each cartridge is pushed up against a stop 
built into the cover of the mechanism, from which 



Figure II. Inside view of protectoscope. 


it is released by the energy from the recoil of the gun. 
The energy in the torsion spring is great enough to 
snap the belt up, forcing the next cartridge in the belt 
against the stop. T he spring is re-tensioned each time 
by the motor. The motor switch operates simultane¬ 
ously with the gun trigger. 

In field tests under Ordnance Department observa¬ 
tion, the device performed satisfactorily, with the gun 
firing freely in its normal manner and the assist-feed 
handling belts of 20 to 50 cartridges, even with addi¬ 
tional weights of 25 to 30 pounds hung on the belt. 

161,6 Turret Seat 

The development of a functional seat was required 
for the gunner in the T-7 light tank turret, with de¬ 
sign features permitting him to use all the guns and 
observation devices with the greatest ease and com¬ 
fort. 



Figure 12. Magazine feed for protectoscope mirrors. 











272 


LAND VEHICLE COMPONENTS 



latch drops into place, locking it in position. When 
he wishes to lower the seat, he releases the latch and 
his own weight overcomes the spring, forcing the 
seat down until the spring-backed latch slips into 
the next slot, locking it in position. 

The seat can be moved forward and back on slides 
with stops at each end and a locking lever to hold 
any desired position. It is capable of full rotation and 
adjustable for height in piano stool style by means 
of a central screw. 


Figure 13. Magazine feed for protectoscope mirrors, new 
mirror being slid into place. 

T-7 Turret Seat 

These requirements were met by a seat enabling 
the gunner to shift to any one of three operating 
heights, slide forward or backward, and turn in a 
complete circle (Figure 16). The three operating 
heights are marked by three stops, one for using the 
360-degree vision device in the turret roof, another 
for sighting the 37-mm gun and controlling the tur¬ 
ret, and a third for using the rear machine gun. 
When the operator wishes to raise the seat, he sup¬ 
ports himself on his feet and trips the handle; a 
strong spring lifts the seat, and a spring-impelled 


1617 Turret Mock-ups 

J he development of ihe gun mounts, protecto- 
scopes, and viewing devices for the T-7 and M-4 tanks 
made it necessary to modify the general turret design 
to accommodate these devices. Mock-ups for the T-7 
turret, incorporating more sloping lines for the sides, 
and for the M-4 turret were prepared. 

1618 Centrifugal Air Cleaner 

Soon after the introduction of motor vehicles to 
desert warfare in 1941, a need became apparent for 
a self-cleaning device to clean the air intakes of tank 
and truck engines. The static or oil-filter type of 
cleaner had not proved satisfactory, requiring a thor- 



Figure 14. Machine gun assist-feed, cover on. 


Figure 15. Machine gun assist-feed, cover off. 












TANK COMPONENTS 


273 



Figure 16. Model of turret seat with three stops for 
operating heights. 

ough cleaning itself after a few hours of exposure to 
desert dust, and no suitable alternate type was avail¬ 
able. 


An investigation was therefore requested by Army 
Ordnance for the development of a self-cleaning 
centrifugal air cleaner to be used on such a vehicle 
as an M-3 medium tank and to meet the following 


chief specifications: 

1. Volume of air flow'at 2,000 rpm . 670 dm 

2. Speed ranges. 500-2,400 rpm 

3. Maximum particle diameter to be passed 

by the filter.5 microns 

4. Maximum space to be occupied . . 3,000 cu in. 

5. Maximum weight. 50-100 lb 

6. Device to be self-cleaning 


l lie two standard types of rotors used in centrifu¬ 
gal separators are the tubular-type rotor and the 
disk-type rotor, the latter containing stratifying disks 
arranged in a stack of cones. After considering the 
dimensions allowable for the device, the size of the 
ducts necessary to carry sufficient air How, and the 
position of the device in the tank, it was decided to 
make the rotor of the disk type, having a stack of 
conical disks with air flowing from the outside of the 
disks inward. Impeller blades were put in the inlet 
section of the centrifuge to bring the incoming air 
up to rotational speed before entering the periphery 
of the rotor. 

The first model constructed, known as the L-5, 
was difficult to install in the M-3 tank, which was de¬ 
signed to accommodate a pair of static-type filters. 
Accordingly, the L-3 centrifugal air cleaner was cle- 































































































274 


LAND VEHICLE COMPONENTS 


signed as a smaller unit, with a capacity ol 350 dm 
and a maximum rotor speed of 8,000 rpm, able to 
handle half the air required by the Wright 975EC2 
engine in the tank. 1 hree models were built. 

Laboratory tests on the L-3 were made by the so- 
called “impinger method to determine the dust- 
separating ability of the cleaner. Similar tests were 
made at the air cleaner test laboratory of the Aber¬ 
deen Proving Ground at Aberdeen, Maryland. No 
held tests were performed. 3 

The construction of the L-3 cleaner is shown in 
Figure 17. The specifications are as follows: 

1. Capacity. 350 cfm 

2. Diameter of intake. 3.625 in. 

3. Diameter of disks.7.5 in. 

4. Number of disks.12 

5. Disk spacing.0- J in - 

6. Disk stack-up.6-0 hi. 

7. Angle of disks."IS 0 


8. Maximum speed of rotor. 8,000 rpm 

9. Weight (with motor).1741b 


The stationary parts of the cleaner are bronze cast¬ 
ings, the rotor castings are aluminum alloy, the disks 
are spun of steel, and the shaft is steel mounted in 
SKF bearings. 

The impinger tests indicated that the L-3 removes 
98.66 per cent of the dust particles and 99.9+ per 
cent of the dust weight. Further analysis showed that 
of the small percentage—about 1.3 per cent—of par¬ 
ticles not removed, about 5 per cent are more than 5 
microns in diameter. 

The tests at Aberdeen, made with an exceedingly 
fine artificial dust expressly designed for efficiency 
tests, showed that 97.4 per cent of the dust by weight 
is removed when the engine is idling, 93.9 at half air 
(1,800 rpm) , and 93.6 at full air (2,200 rpm). 

These figures show the L-3 cleaner to be superior 
to the static-type cleaners at engine idling speed, less 
efficient at half air flow, which is the usual engine re¬ 
quirement, and still less efficient at full air flow. Fig¬ 
ure 18 shows the relative performance of the L-3 
cleaners and an oil-bath static cleaner on a weight 
percentage basis. 

An advantage of the L-3 self-cleaning centrifugal 
air cleaner over static-type filters is its constancy 
of pressure drop. Its greatest single advantage is its 
relative freedom from servicing requirements. The 
L-3 automatically ejects the dust separated from the 
air, whereas the static types must be taken apart, 
cleaned, freshly oiled, and reassembled every day 
for optimum service. However, the L-3 will not ex¬ 


tract a sufficiently high percentage of very small par¬ 
ticles (less than 5 microns), and accordingly its use 
is not recommended for this duty. 

1619 Conclusions 

No items developed in this project were put into 
production. 

162 MOBILE ROCKET LAUNCHERS 0 
Summary 

In cooperation with other divisions of NDRC, Divi¬ 
sion 12 recommended that the DUKW be equipped 
to carry rocket-launching devices and used to supply 
additional fire power for amphibious assaults. The 
Scorpion launcher designed in this research was in¬ 
corporated in several DUKWs which were sent to the 
Southwest Pacific, while other units were dispatched 
to the European Theater of Operations. In the Pacific 
Ocean Areas, after a token rehearsal at Milne Bay in 
November 1943, the rocket-carrying DUKWs were 
used in the assaults on Arawe, Cape Gloucester, Sai- 
dor, and other island objectives, inaugurating the 
rocket beach barrage technique. 

e Project “Scorpion.” 



60 120 180 240 300 360 

AIR FL0W-CFM 

Figure 18. Comparison of performance of centrifugal air 
cleaner and static filter air cleaner. 






























MOBILE ROCKET LAUNCHERS 


275 


16,21 The Problem 

At the request of a special committee of the Joint 
Chiefs of Staff and the Joint Committee on New 
Weapons and Equipment, Division 12 undertook a 
study in October 1942 on the equipping of combat 
vehicles with rocket-launching devices. It was be¬ 
lieved desirable that these devices be so designed that 
they could be used on various vehicles, amphibious 
or nonamphibious, and could also be removed for use 
on the ground. 

Procedure 

A preliminary survey of this problem resulted in a 
recommendation that the rocket launcher be devised 
for use on either the amphibious or the nonamphib- 
ious 14 -ton, 4x4 jeep. Later, however, the DUKW ' 1 
was chosen as the basic vehicle because it could mount 
a greater fire power of rockets. The DUKW installa¬ 
tion was then designed for the 1,100-yard 4.5-inch 
Beach Barrage Rocket [4."5 BBR], which had already 
been brought to an advanced stage of development by 
the California Institute of Technology [CIT], a con¬ 
tractor under Division 3 of NDRC. 

A fleet of DUKWs had already been assigned to 
the Second Engineer Special Brigade [2nd ESB], then 
completing its final training at Fort Ord, California, 
and preparing to embark for Australia. One of the 
brigade’s DUKWs was sent to CIT and work began 
on January 19, 1944. Since the brigade was scheduled 
to embark in about a week, an installation was impro¬ 
vised from elements already available. This consisted 
of sheathing the cargo space of the DUKW with sheet 
metal for protection against rocket blasts, providing 
a protective sheet metal canopy over the cab, and 

•i See Chapter 3 in this volume. 



Figure 19. Early model of Scorpion rocket launcher for 
DUKW. 


then mounting three so-called “crate” launchers side 
by side across the center of the cargo space. Each 
crate, previously developed by the CEE group for fir¬ 
ing a 4."5 BBR from support boats, consists of four 
tiers of rails, with three sets of rails in each tier. 

The CIT group completed the installation on the 
night of January 20, and the DUKW was then driven 
to Fort Ord for demonstration firings on January 22 
and 23. Following the demonstration, the command¬ 
ing general of the 2nd ESB reported that the barrage 
pattern was excellent and thereupon shipped the im¬ 
provised rocket DUKW to the Pacific with his men. 
I 11 return, he released two standard DUKWs to CIT 
for use in the further development of a launcher. 

With more time available, it was possible to design 
a new launcher with a capacity of 144 rounds of 4."5 
BBR. By March 18, 1943, an improved version of this 
launcher had been manufactured as a proposed pilot 
model and was ready for test . 0 This launcher was com¬ 
posed of 12 separate units or subassemblies, each con¬ 
sisting of a rack of 12 5-foot tubes or barrels fixed in 
line fore and aft and inclined forward at a quadrant 
angle of 45 degrees (Figure 19). The lower ends of 
these barrels vented into a tube which formed the 
bottom of the rack and which was designed to stop 
the flame from the rocket blast, while small perfora- 

e This unit was manufactured by the General Motors Cor¬ 
poration. Detroit, Mich. 

f 



Figure 20. 4."5 barrage rocket fire from Scorpion. 















276 


LAND VEHICLE COMPONENTS 



Figuri 21. Improved Scorpion rocket launcher installed on DUKW. 


tions in the end permit the blast gases to escape. 
Field tests (Figure 20) indicated the need of various 
minor modifications, including the reduction of the 
number of barrels in each unit from 12 to 10, giving 
a total capacity of 120 rounds (Figure 21). A fire con¬ 
trol box designed by the manufacturer was added so 
that the co-driver could use a motor-driven selector 
switch to “ripple-fire” a complete salvo of 120 rounds 
in 1 minute or to fire single rounds as desired. This 
launcher was designated the CIT Type 6 Mod 1 
launcher for the 4."5 barrage rocket. 7 Four of these 
units were then manufactured and shipped overseas 
early in August 1943 to the 2nd ESB which, having 
completed its training in Australia, had joined the 
combined Australian and American forces operating 
along the coast of New Guinea. 

At the same time, 10 additional launchers were 
obtained to meet urgent cable requests from the 
European theater, and subsequently about 150 
launchers were ordered for use in future European 
operations. 

A second type of launcher was later developed to 
enable the DUKW to fire 7."2 rockets. This project, 
undertaken at the request of NDRC to deal with the 
special demolition problems which would be in¬ 
volved in the invasion of Europe, was directed almost 
entirely by Division 3. s After a series of demonstra¬ 
tions at Fort Pierce, Florida, in February 1944, dur¬ 
ing which military observers reported favorably on 
its operation, this device went into production. No 
field requirement, however, was ever formally con¬ 


firmed, and the informally requested installations— 
approximately 100—were never used. 

16 2 2 Results 

Even though the five rocket DUKWs sent to the 
2nd ESB had been urgently requested for virtually 
immediate use, representatives of Division 12 found 
on arrival at Milne Bay in New Guinea that they had 
been warehoused there for about 3 months. The 
NDRC representative then staged a token rehearsal 
of these units in November 1942 and indicated to the 
military authorities the possible tactical uses of these 
vehicles. On December 15. 1943, two of these rocket 
DUKWs spearheaded the landing at Arawe on New 
Britain Island, giving the 2nd ESB the distinction 
of being the first to use barrage rockets in an am¬ 
phibious operation in the Pacific. At daybreak the 
DUKWs preceded the waves of amphibious tractors 
and landing craft and poured out a deadly fire on the 
beach on which the landing was made. Because of the 
configuration of the beach the rocket DUKWs were 
able to continue the fire until the leading wave of am¬ 
phibious tractors was only 200 yards from the beach 
proper. Only scattered shots were received from the 
beach as the heavy rocket barrage obviously smoth¬ 
ered the Jap defenders. The fire power which these 
rocket DUKWs laid on the beach just at the last mo¬ 
ment before the waves landed was so destructive, it 
was reported by the commanding general of the bri¬ 
gade, that their example was followed in all later 














MOBILE ROCKET LAUNCHERS 


landings in the Pacific. For the next 6 months, the 
rocket DUKWs were used by the 2nd ESB in nearly 
every amphibious operation to which this group was 
assigned. In the landing on Cape Gloucester in New 
Britain, they laid down a preparatory barrage for the 
assault on a beach objective. They were used also in 
the Saidor landing, the Hollandia operation, the as- 
sanlt on Tanamerah, and the invasion of Biak. In 
many of these operations, after the DUKWs had laid 
down their barrage to cover the initial landings, they 
were used regularly for “end runs” to extend the 
beachhead. They were used to destroy enemy bar¬ 
rages in water too shallow for PT boats. In some cases 
they were also driven ashore and used as the troops 
advanced inland, taking on the function of small 


tanks and knocking out enemy gun emplacements 
and strong points which were holding up infantry 
advances. 

The rocket DUKWs were seldom used alter the late 
spring of 1944. This resulted partly from the fact that 
no more replacement launchers were forthcoming, 
but especially from the fact that the 2nd ESB had 
found the LVT (Buffalo) better suited to its general 
needs for an amphibious rocket vehicle. Although 
the LVT has less rocket-carrying capacity than does 
the DUKW, it was found to be more able to negotiate 
reefs, pot-holes, and muddy terrain, and its rocket 
fire for landing operations cotdd be better supple¬ 
mented by that of other rocket craft which were a 
regular part of the battalion’s support battery. 






Chapter 17 

LAND VEHICLE STUDIES 


17 * TANK NOISE REDUCTION 1 
Summary 

n an effort to reduce the noise of production models 
of the M-3 light tank, tests and modifications were 
made on a number of light and medium tanks manu¬ 
factured by Marmon-Herrington and General Mo¬ 
tors. As a result of these studies, it became possible 
to reduce the noise of the M-3 light tank to approxi¬ 
mately one-third of its usual level. 

This was accomplished in part by acoustic treat¬ 
ment of the crew compartment, the engine compart¬ 
ment, and the air intakes and outlets, and by the use 
of the most quiet types of tracks, but largely by the 
application of an adequate muffler and the installa¬ 
tion of suitable rings or blocks to absorb the shock 
of the impact of the track blocks on the sprocket teeth. 

No practical use was made of either the sprocket 
teeth silencers or the improved mufflers, although, 
largely as the restdt of renewed tactical requirements 
for night flanking during the Battle of the Bulge in 
the Ardennes, military interest was temporarily re¬ 
newed in the development of quiet mufflers. 

1711 The Problem 

During the early part of 1941, it became apparent 
to the U. S. Army Ordnance Department and to 
several tank manufacturers that tanks currently com¬ 
ing off the production lines were excessively noisy. 
This noise included not only “tactical” or outer 
noise, which would serve to warn enemy observers of 
the proximity of the tank, but also “crew environ¬ 
ment” or inner noise, which interferes with inter¬ 
communication by crew members and presumably 
induces fatigue. 

Research was consequently instituted first to meas¬ 
ure the noise produced by selected light and medium 
tanks, with special attention to that produced by their 
tracks and sprockets, and then to develop effective 

a Project OD-19. 

b These measurements were made by the Cruft Laboratory, 
Harvard University, Cambridge, Mass., under the National Re¬ 
search Council Committee on Sound Control, and reported in 
reference 1. 


methods of control which cotdd be applied without 
radical changes in tank design. 

It had already been reported by other workers that, 
in so far as tactical noise is concerned, the most ob¬ 
noxious are the high-frequency noises resulting front 
sprocket clatter, and accordingly it was felt that par¬ 
ticular emphasis should be placed on controlling this 
source. 

1712 Procedure 

Preliminary listening tests were conducted on the 
Marmon-Herrington CTL-6 light tank and CTM- 
3TBD medium tank, which were equipped in turn 
with steel tracks, rubber block tracks, and continuous 
rubber tracks with steel idlers, and then run over 
concrete, gravel, and dirt surfaces. Sound levels were 
determined with a microphone placed in eight dif¬ 
ferent positions inside and outside each tank and 
connected to equipment which measured the levels 
in different frequency bands. It was found that the 
track with its associated idlers and sprockets is the 
principal source of noise, and that any noise reduc¬ 
tion of these two tank models must involve an im¬ 
provement of these components. 11 

This investigation was then continued on the Gen¬ 
eral Motors M-3 light tank. 0 The first measurements, 
including objective sound measurements and “jury 
tests,” with observers judging the detectability of 
tanks, pointed to a number of individual factors 
which contribute in different degrees to tank noise. 
Each of these factors was considered in turn and an 
effort made to find the most practical solution. 

Sprocket Noise 

In order to determine the means by which sprocket 
clatter is generated, high-speed motion pictures were 
made under operating conditions,* 3 and particular at¬ 
tention was directed to the point of track engage¬ 
ment. These indicated that, as far as approach to the 
sprocket is concerned, the track fails to act as a flexi- 

c This investigation was conducted by the General Motors 
Corporation, Proving Ground Section, Milford, Mich., under 
OSRD contracts OEMsr-460 and OEMsr-870. 

d Made by Edgerton, Germeshausen and Grier, Cambridge, 
Mass., under OSRD contract OEMsr-26. 



‘>78 






TANK NOISE REDUCTION 


279 



Figure 1. Rubber rings installed on M-3 light tank to re¬ 
duce sprocket noise. 


ble band. Instead of moving toward the sprocket 
along a line tangential to the pitch circle, the ap¬ 
proaching track blocks come in above the tangential 
line, and on engagement swing in radially to seat on 
the shoulders of the sprocket teeth. This action is 
probably due to the stillness of the track and the 
track joints. The impact with which the inward ra¬ 
dial motion ends was tentatively considered as the 
principal excitation for sprocket clatter, and subse¬ 
quent tests tended to confirm this view. 

In a preliminary attempt to silence the sprockets, 
damping material was applied to the complete 
sprocket assemblies in the form of a half-inch coating 
of an asphalt-sand mixture which was baked on the 
hubs and teeth, both inside and out. This coating 
was quickly found to be impractical and perishable, 
and moreover gives a reduction of only about 3 db. 

It was next determined that no measurable im¬ 
provement could be obtained by cutting away the 
shoulders on the sprocket teeth. 

The final modification involved the addition of 
rubber shock absorbers. In one case the absorber is 
in the form of a rubber ring held between metal 
bands and designed to bear the radial loads at the 
sprocket while the tangential driving forces are borne 
by the sprocket teeth. e (See Figure 1.) In the other it 
consists of small rubber blocks bonded to metal 


e in this form tlie rubber rings are analogous to those on the 
Canadian Mark III Valentine Tank and serve the same purpose. 



Figure 2. Rubber blocks installed on M-3 light tank to 
reduce sprocket noise. 


mounts which fit in between the sprocket teeth and 
are welded in place (Figure 2). 

Listening tests were run on the M-3 tank equipped 
with these modifications and with different kinds of 
tracks. 

Muffler Noise 

Several muffler designs were tested and compared 
with the production mufflers currently being in¬ 
stalled on the M-3. With twin mufflers of the same 
size and shape as those used on production models, 
any attempts to reduce noise resulted in most cases 
in higher back pressure and less satisfactory tank 
performance. The most satisfactory of the double 
muffler type was found to be the Hayes No. 2A459. f 

Much better results were achieved with a single 
muffler, particularly the Nelson T-1619, with a single 
tail pipe for the whole engine (Figure 3). K Moderate 
improvement could be obtained by adding to the 
production muffler a tail pipe 2 i /9 inches in diameter 
and 20 inches long. 

Misfiring Noise 

In production model tanks, it was found that when 
the throttle is closed at high engine speeds, the en¬ 
gine misfires and then ignites the unburned charge 
in the exhaust manifold. The correction of this noise 


f Manufactured by Hayes Industries, Inc., Jackson, Mich, 
g Manufactured by the Nelson Muffler Corp., Stoughton, Wis. 











280 


LAND VEHICLE STUDIES 





was not undertaken in this investigation but referred 
to the manufacturer for appropriate action. A de-fum- 
ing device was designed by the manufacturer for the 
M-3 engine. 

Engine Compartment Noise 

A first attempt at reducing the tactical noise from 
the engine compartment consisted of the application 
of large conduits or ducts lined with sound-absorbing 
material. These were fastened to the exterior of the 
tank, one being applied to the engine air-intake open¬ 
ing and the other to the exhaust and cooling air out¬ 
let, as shown in Figure 4. 

To reduce engine compartment noise reaching the 
crew compartment, the oil coolers were enclosed and 
the engine compartment sealed except for an ab¬ 
sorbent-lined duct through which cooling air could 
be drawn. This duct replaces the propeller shaft 
cover of the production tank. Air enters the duct 
through openings near the transmission casing and 
travels parallel to the propeller shaft toward the 
rear, where it branches out into the oil cooler en¬ 
closures. 

Sound-Absorbing Lining 

As a further step in reducing inner noise, a highly 
absorbent layer of l^-inch hair and asbestos felt was 
applied to all the accessible wall surfaces. The pro¬ 
duction tank, with its hard metallic interior surfaces, 
offers negligible sound absorption, and consequently 
it was expected that the introduction of even mod¬ 
erately effective sound-absorbing material would give 
appreciable improvement. 

Track Rumble and Hull Vibration 

A major source of low-pitched noise in the tank 
interior was traced to the relation between the bogie 
wheels and the tracks. In the production track, a gap 
exists between successive tread blocks, and the bogie 
wheels tend to sink into this gap as they cross from 
one block to the next. If, as in the production M-3 
light tank, the spacing between wheel centers on the 
same bogie assembly is equal to an integral multiple 
of the tread block length, both of these wheels sink 
into the gaps simultaneously, and their motions are 
in phase. Under these conditions a strong vibratory 
force is transmitted through the spring suspension to 
the hull of the tank and results in a low-frequency 
rumble which tends to vary considerably in intensity 
as the two tracks move relative to each other. The vi- 


Ficure 4. Installation of sound-absorbing ducts on M-3 
light tank. 


Figure 5. Types of track treads tested for noise reduc¬ 
tion: U. S. Rubber (left), production type (center), Good¬ 
rich (right). 


Figure 3. Installation of Nelson T-1619 muffler on M-3 
light tank. 



















TANK NOISE REDUCTION 


281 




0-0.5 0.75-1.5 1.5-3 3'6 6-12 12-24 24-48 

0.5-1 1-2 2-4 4-8 8-16 16-32 >48 

C/100 


0-0.5 0.75-1.5 1.5-3 3-6 6-12 12-24 24-48 

0.5-1 1-2 2-4 4-8 8-16 16*32 >48 

C/100 


Figure 6. Effects of control measures on tactical noise of M-3 light tank. 


bration also causes severe rattling of the turret and 
other parts of the tank at certain speeds. 

In order to reduce the low-frequency bogie wheel 
rumble by producing an out-of-phase relationship 
between the bogie wheel motions, a U. S. Rubber 
Company track with a shorter block length was sub¬ 
stituted for the standard track. In another attempt, 
a B. F. Goodrich Company track presenting a much 
smoother surface to the bogies was tested (see Figure 
5). 

,71 - 3 Results 

The effects of these various modifications in reduc¬ 
ing tactical noise arc shown in Figure 6. An average 


over-all reduction of more than 6 db is obtained on 
sprocket noise by use of the rubber rings and of about 
5 db by use of the rubber blocks. The reduction is 
particularly noticeable in the higher frequencies. 

With muffler noise measurements taken 15 feet 
from the rear of a stationary tank and with the engine 
idling at 2,000 rpm, an over-all reduction of about 
7 db is obtained by addition of a tail pipe to the pro¬ 
duction muffler, and of more than IS db by substitu¬ 
tion of the Nelson T-1619 muffler. The effects are 
most noticeable in the lower frequencies. 

An over-all reduction of more than 4 db results 
from adding sound-absorbing ducts for air inlet and 
outlet, with measurements made behind the station- 




























282 


LAND VEHICLE STUDIES 



0.5*1 1-2 2*4 4-8 8-16 16*32 >48 

C/100 



0.5-1 1-2 2-4 4-8 8-16 16-32 >48 

c/ioo 


Figure 7. Effects of control measures on inner noise of M-3 light tank. 























REDUCTION OF BOUNCING IN TOWED GUN CARRIAGES 


283 


ary tank already equipped with the T-1619 muffler 
and the engine idling at 1,500 rpm. 

Use of the Goodrich smooth rubber track gives an 
over-all reduction of about 5 clb on a tank already 
equipped with the T-1619 muffler. 

A combination of these controls gives an over-all 
reduction of abotit 8 db. 

The results in reducing inside noise are illustrated 
in Figure 7. An over-all reduction of more than 5 db 
is given with the T-1619 muffler, about 1 db with rub¬ 
ber rings, about 1 db with felt linings, about 1 db with 
an insulated cooling air tunnel, and about 2 db with 
the Goodrich smooth rubber track. The combination 
of all these controls gives an over-all reduction of 
about 9 db. 

In jury tests, seven observers recorded the time at 
which they first heard the tank—either an unmodified 
production model or an experimentally modified 
tank—approaching across a turf field. Rough com¬ 
parisons indicated that the unmodified tank could 
be heard on the average at 800 yards, and while start¬ 
ing and shifting gears at 1,270 yards. Addition of the 
Nelson muffler reduced this average to 615 yards, 
and the installation of sound-absorbing material 
around the tracks and around the cooling air inlet 
and outlet reduced it still more to 515 yards. 

Neither the newly developed sprocket teeth si¬ 
lencers nor the improved muffler found application 
to production tanks. Very late in the war, the Army 
requested further study of the sprocket teeth devices, 
but this was cancelled soon after the surrender of 
Germany. Considerable interest developed in muf¬ 
flers shortly after the Battle of the Bulge in the winter 
of 1944-45, and a project was set up to test commer¬ 
cially manufactured mufflers for use in quieter tank 
operations. Although satisfactory mufflers were de¬ 
signed and built, they were not released for produc¬ 
tion. 

1714 Conclusions 

By combining the noise reductions obtainable by 
rubber sprocket rings or blocks and good mufflers, the 
external or tactical noise of the M-3 light tank can be 
reduced at least 8 db over the whole frequency range, 
and nearly 10 db over-all. This corresponds to a re¬ 
duction of the sound pressure to one-third of its 
original value. It also means that the average audible 
distance will be reduced to perhaps one-third of that 
for a production tank, depending on the ambient 
noise at the listening point. 


Further reduction in the tactical noise can be ob¬ 
tained by a sound-absorbing lining for the engine 
compartment, by track and suspension changes, and 
by absorbing ducts for the engine air intake and out¬ 
let. However, the elimination of misfiring and sprock¬ 
et clatter and the installation of belter mufflers 
remain the prime requirements for satisfactory noise 
reduction over the whole frequency spectrum. 

In the case of inner noise, low frequencies are 
diminished by muffling and by track changes, and 
middle and high frequencies are reduced by sound- 
absorbing linings and sprocket rings, and by the seal¬ 
ing off of the engine compartment. The net result is 
a reduction sufficient to enable the crew to carry on 
intelligible conversation throughout the speed range 
of the tank. 10 

File use of rubber rings, while excellent from a 
noise reduction point of view, is not a satisfactory 
solution from a practical point of view. The clear¬ 
ance between sprockets and tank hull is excessively 
diminished, and several rivets cause interference with 
the extended track guides. It appears that the use of 
bonded rubber blocks is more practical, giving equiv¬ 
alent noise reduction without introducing interfer¬ 
ence problems. Although the rubber blocks as used 
prove somewhat less quieting at high speeds than do 
the rubber rings, a slight redesign should be able to 
restore the full quieting efficiency. 13 

Although it had been reported earlier by other 
workers that the high-frequency sprocket clatter of a 
tank is the most important source of noise in enabling 
distant observers to detect it, this is not confirmed by 
the present investigation. In general, it appears that 
the low frequency of muffler noise is at least as im¬ 
portant. Only when the ambient noise is rich in low 
frequencies does the detectability of a tank depend 
primarily on sprocket noise. 8 


17 2 REDUCTION OF BOUNCING IN 
TOWED GUN CARRIAGES 

Summary 

Design changes in (1) gun carriage suspension, in¬ 
cluding increased wheel travel, increased width, de¬ 
creased spring rate, and increased damping, and in 
(2) gun carriage tow connections, including damp¬ 
ing, have been recommended to give needed improve¬ 
ment in performance during towing. 





284 


LAND VEHICLE STUDIES 


17-2 - 1 The Problem 

Observation indicated that two-wheeled gun car¬ 
riages without spring suspension occasionally under¬ 
go serious bouncing when towed on a hard road. In 


addition, four-wheeled carriages with spring suspen¬ 
sion, including 37- and 47-min types, have been 
found subject to damage when towed over a rough 
road. 



l w.rki S. Proposed Design A for tour-wheeled gun carriage suspension. 





























































































REDUCTION OF BOUNCING IN TOWED GUN CARRIAGES 


285 



Figure 9. Proposed Design B for four-wheeled gun carriage suspension. 


































































































286 


LAND VEHICLE STUDIES 


An investigation was required to devise design 
changes which would eliminate or greatly reduce this 
characteristic. 11 

1722 Conclusions 

Two- Wheeled Carriages 

In the case of two-wheeled carriages without spring 
suspension, the damping attending free vibration on 
a hard road is so limited that serious bouncing would 
be expected as a result of wheel unbalance or of 
bumps having a component of period equal to the 
natural period. In the case of a soft road, such a 
resonance would be undoubtedly much less severe 
because of the damping in the road material. 

Even without radical changes in the design of the 
two-wheeled carriage, considerable improvement may 
be obtained by adding vertical flexibility between the 
carriage and the point of attachment to the towing 
vehicle, and by providing damping across this flexi¬ 
bility. If this damping were large enough, it would 
tend to eliminate rather than merely reduce the pos¬ 
sibility of a sell-excited bouncing on a smooth road, 
and it would tend to reduce but not eliminate the 
amplitude of vibration on a hard, rough road. It is 
expected that the addition of such damping would 
not improve performance over a soft road. 

Four-Wheeled Gun Carriages without 
Spring Suspension 

No material improvement in this type of carriage 
is suggested. It seems likely that, because of pin fric¬ 
tion, considerable damping is already present to re¬ 
duce almost any mode of bouncing. Because of this, 
there seems to be no need to add damping either as 
proof against periodic bouncing on a smooth road or 
as a means to reduce bouncing on a hard, rough road. 

Four-AVheeled Gun Carriages with 
Spring Suspension 

In a study of the 37-, 40-, and 90-mm guns, it was 
found that, in the case of at least the first two, damage 
has occurred from hitting the stops at the ends of the 
sprung travel of the wheel. This could be reduced by 
(1) increasing the damping by the addition of shock 
absorbers, (2) increasing the travel between stops, (3) 


11 This investigation was undertaken by the Baker Manufac¬ 
turing Co.. Evansville, Wis., under OSRD contract OEMsr-524. 


providing deep resilient bumpers instead of slops, 
and (4) increasing the spring rate. Any one of these 
steps or a combination of them would be expected 
to have a beneficial effect. At times when there is no 
impact, steps 1 and 2 would usually improve the ride, 
but generally the greater the spring rate, the harder 
the ride. On the other hand, if the spring rate is re¬ 
duced and the tendency to hit the stops is compen¬ 
sated by steps 1 and 2, the ride is improved but the 
point is soon reached where the side sway on turning 
becomes excessive. Side sway can be minimized by 
using as wide a wheel spread as is practical. It can also 
be reduced by using a torsion spring connection be¬ 
tween wheels, but this increases the spring rate for 
bumps on only one side. 

A further study of the 37-mm gun carriage indi¬ 
cated that the carriage would tend to squat when the 
brakes were applied, and that the slotted joint used in 
current models is somewhat vulnerable to dirt and 
wear. 

In addition to design changes of increased wheel 
travel, increased width, decreased spring rate, and 
increased damping, it appears that the method of rais¬ 
ing and lowering the wheels could be simplified. It 
also seems that the same type of design should be 
used on all sizes of carriages, at least up to those using 
two tires per wheel. Two carriage suspension designs 
have been suggested, both using parts taken from 
standard automobiles. 

In the scheme shown in Figure 8, Chevrolet front- 
wheel springs, brake drums, shock absorbers, and 
rubber bumpers are mounted on the sub-frame, 
which is hinged at the frame of the gun carriage. The 
wheel may be raised or lowered by rotation of a spe¬ 
cial screw. When the wheel is lowered, a rod stops 
the travel in the ride position. The steering from the 
tongue is more or less conventional. The spherical 
joints are placed so that the wheel may be raised 
without interference. 

Figure 9 shows a scheme which is adaptable either 
to the leaf-spring suspension illustrated here or to 
the knee-action type of wheel suspension. The leaf 
spring, ride stabilizer, axle, etc., are all mounted on 
the frame which is hinged on the main frame. The 
wheels (not shown) may be raised or lowered by rotat¬ 
ing the screw. A rod serves as a stop when the wheel 
is lowered. 1 he steering is conventional. The towing 
tongue is hinged at a point which will not interfere 
with rotation of the frame about the pin. 17 








Chapter 18 


SPECIAL DEVICES 


18 1 LANDING WHEEL BRAKES 
Summary 

I mproved aircraft brakes with a capacity of energy 
absorption in the form of heat of 25,000 ft-lb per sq 
in. of braking surface have been developed to meet 
the specifications for such heavy bombers as the B-17, 
the B-24, and the B-29. This achievement, marking a 
threefold increase in capacity, has resulted largely 
from careful planning, cooperative effort, and ex¬ 
change of data. 1 he use of powdered metals in brake 
linings has been of great importance, as has the im¬ 
proved design of brake structures. 

1811 The Problem 

In May 1941, an investigation was undertaken on 
expanding, contracting, and disk-type mechanical 
brakes, together with recommendations for increas¬ 
ing their braking capacity and reducing their size and 
weight. a When the study began, it was generally ac¬ 
cepted that 6,000 ft-lb per sq in. of braking surface 
was the maximum that could be absorbed and dissi¬ 
pated in the normal stopping time. This limit, it had 
been reported, could not be materially exceeded with¬ 
out warping, shrinking, and cracking the plates, as 
well as very rapidly deteriorating the lining. Several 
types of cast-iron and laminated steel plates had been 
developed, but gave only minor improvement. 

Meanwhile, however, the Armed Services were 
planning the construction of very heavy bombers 
with unprecedented weight and landing speed. Speci¬ 
fications for such planes as the B-17 Flying Fortress, 
the B-24 Liberator, and the B-29 Superfortress called 
for braking capacities of 14,500 ft-lb per sq in. 

181,2 Procedure 

To aid in meeting these specifications, the National 
Research Council acted as a coordinating agency, se¬ 
curing cooperation from the industry, formulating 

a This investigation was conducted by the National Research 
Council, Division of Engineering and Industrial Research, the 
Society of Automotive Engineers, and representatives of the in¬ 
dustries and branches of the military services concerned. 


plans for investigation, obtaining and transmitting 
necessary information, 3 suggesting design modifica¬ 
tions, and urging development along specific lines. 
Funds were available to subsidize a certain amount of 
experimental work, but it was found that industry 
preferred to bear the costs of its own research, and this 
policy was encouraged. 

The first extensive research program was directed 
toward obtaining materials with thermal conductiv¬ 
ity high enough to remove the heat from the rubbing 
surfaces before the temperature would rise to destruc¬ 
tive values. Powdered metal appeared to have the de¬ 
sired heat-conducting ability, and was tried in several 
forms but at first without success. It was then sug¬ 
gested that the powdered metal in a % 6 -inch thick 
facing be fused to a rolled copper plate. In tests with 
an Adamson dynamometer, these plates made 313 
successful runs at a load of 10,000 ft-lb per sq in., 100 
at 15,000, 61 at 20,000, and 10 at 25,000 before the test 
was discontinued. 

New linings were required to work with these pow¬ 
dered metals, and these were successfully developed 
by several lining manufacturers. Improvement also 
became essential in the physical characteristics of the 
steels used for the shells and of the cast-iron alloys, 
and these, too, were made by the industries. 

181,3 Results 

With the demonstration that the unit loading of an 
aircraft brake is not limited to the previously assumed 
6,000 ft-lb per sq in. of rubbing surface, research was 
stimulated on a reassessment of other braking factors, 
and on the development of actual brakes for installa¬ 
tion on aircraft. The resulting new products are now 
in service. 

One small brake for a 7.50x10-inch wheel, origi¬ 
nally rated at 4,000 ft-lb per sq in., has been equipped 
with a powdered metal facing and is rated at better 
than 7,000. Another, with powdered metal and with 
one of the new brake linings, operated satisfactorily 
on the B-19, and is now being manufactured in the 
smaller sizes with a claimed unit loading of 10,000 ft- 
lb per sq in. and a probable loading of 15,000. A third 
has passed complete load tests at 19,900 ft-lb per sq in. 




287 




288 


SPECIAL DEVICES 


Another on a 56-inch wheel was run at a load of 
14,450 ft-lb per sq in. of rubbing surface (totalling 
10,000,000 ft-lb) at a landing speed of 123 mph and in 
a stopping time of 15.25 seconds, and successfully 
passed 100 consecutive test stops. 

1814 Conclusions 

Adequate aircraft brakes have been made available 
for the planes which were in quantity production 
when this study was terminated. 9 Experimental data 
and other information have been accumulated which 
should make it possible to meet requirements of the 
new and larger planes still in the stage of design and 
development. For given size and weight, brakes can 
be made with capacities at least three times that which 
they had when this research project was started; and 
the end is by no means in sight. 

This has resulted largely from careful planning, 
cooperative effort, and exchange of data rather than 
from radically new 7 principles of operation. Particu¬ 
lar consideration was given to problems of heat trans¬ 
fer, suitable design to provide for inevitable expan¬ 
sion and contraction, and the development of new 
friction materials. No radically new brake designs or 
ideas w r ere uncovered that could withstand the test of 
experienced scrutiny. 

Powdered metallurgy has played a very important 
role in producing friction surfaces which eliminate 
“grab” and maintain an approximately constant fric¬ 
tion coefficient over a wide range of temperature. 
Only a beginning has been made in the determina¬ 
tion of the properties of various possible mixtures. 
This research should and doubtless will be continued. 

18 2 BOMB RACKS b 

Summary 

In an attempt to improve on the Mark 51 Mod 7 
bomb rack used by Navy bombers, tw 7 o new designs, 
the Mark 51 Mod 11 and the Mark 54 Mod O, were 
prepared and a small number of units delivered to 
the Bureau of Ordnance. In preliminary trials, they 
appeared to offer some improvements over the older 
model both in releasing and in arming the bombs. 

i> Project NO-233. 


,8 - 21 The Problem 

Reports of serious operational service failures of 
the Mark 51 Mod 7 bomb rack prompted an investi¬ 
gation to determine as rapidly as possible the causes 
and conditions for failure and to design equally 
rapidly an interim device which would meet an ur¬ 
gent need for a dependable bomb rack. 

18 2 2 Development of Mark 51 Mod 11 
Bomb Rack 0 

Procedure 

Laboratory tests of production models ot the Mark 
51 Mod 7 rack revealed several types of failure, in¬ 
cluding failure to release and to arm the bomb at low 7 
temperature, a tendency to release by vibration, and 
a condition in which the bomb failed to disengage 
from the hooks after it had been released. 

Failure to release the bomb at low temperature was 
due chiefly to the stiffening of a rubber sealing cap 
which effectively resisted the release solenoid force. 
Lhe release solenoid was found to be inadequately 
designed for such a critical item. 

Failure of the electric arm and safe function was 
due to inadequate solenoid and return spring force to 
overcome icing resistance at low 7 temperatures. 

The use of tectyl rust preventive contributed to the 
failures of both the release and arming functions. 
Tests in which failures were observed w 7 ere made on 
racks cleaned with tectyl. 

Flic tendency of the rack to release under vibration 
was discovered to be due to play allowing the release 
solenoid plunger to hammer against the release lever. 

I'he type of failure in which the bomb failed to 
disengage from the hook after release of the rack 
was found to be due to a basic error in the location 
of the hook pivot point in the original rack. As a re¬ 
sult, the friction of the hook in sliding out from under 
the bomb lug could effectively oppose the opening 
of the rack. 

Since the relocation of the hook pivot point would 
have involved a complete redesign of the rack frame 
and mechanism, which would have been too time- 
consuming for an interim device, the steps taken to 
correct this type of failure were confined to modifica¬ 
tion of the shape of the hook by providing a 7y 9 - 

c This investigation was conducted by the Douglas Aircraft 
Company, Inc., El Segundo. Calif., under OSRD contract 
OEMsr-1435. 









BOMB RACKS 


289 


degree downward slope to the bomb lug carrying sur¬ 
face, and later the local induction-hardening of this 
surface to reduce brinelling and friction. Strength 
tests of numerous hook samples indicated that the in¬ 
duction-hardening should be carried out carefully to 
avoid introducing brittleness and weakening the 
hook. 

Rack components designed to correct the faults 
noted above were built, tested, and installed in five 
sample racks, which were delivered to the U. S. Navy 
Bureau of Ordnance for testing. Although the modi¬ 
fied racks were basically satisfactory in performance, 
the Bureau of Ordnance requested further design 
changes involving the arming retainer housing, the 
bomb hooks, and the electric arming control. The 
introduction of a specific arming solenoid coil tem¬ 
perature limitation at an increased voltage necessi¬ 
tated considerable redesign and testing in an effort to 
meet the heat requirement and yet to retain sufficient 
solenoid pull for cold-weather operation. 

In the course of the investigation, in which a large 
number of racks were observed completely dis¬ 
mantled for cleaning prior to installation on air¬ 
planes, there was considerable evidence of faulty 
manufacture and of a low standard of inspection on 
the functional parts. 

Results 

The Mark 51 Mod 11 bomb rack, incorporating all 
Bureau of Ordnance requirements, was constructed 
as shown in Figure 1, and eight units were submitted 
to the Navy. 3 The upper part of the illustration 
shows the old Mod 7 rack with the upper side made of 
transparent plastic and portions of some parts cut 
away to reveal internal mechanism and construction. 
In the lower part are the redesigned parts to replace 
corresponding parts in the older model. 

Shown here are the wire cover (A), the hoist slot 
cover plate (B), the release unit assembly with rede¬ 
signed solenoid (C), grommets for release solenoid 
wiring (I)), control cable bushings (E), latching screws 

(F) , release solenoid wiring with quick disconnects 

(G) , redesigned arming unit assembly, shown here 
with arming retainer pull-out guard (H), the hook as 
redesigned by the Bureau of Ordnance (I), the re¬ 
worked hook from the Mark 51 Mod 7 rack (J), hook 
pivot pin washers (K), and hook pivot pins (L). 

In laboratory tests, the release unit of the new rack 
appears to be thoroughly dependable for low-temper¬ 
ature operation and has no tendency to release from 


vibration under 3,000 rpm and under .030-inch total 
displacement. The solenoid pidl required to release 
the rack has been reduced. The solenoid force avail¬ 
able has been increased, as have both the theoretical 
minimum load on the rack and the theoretical mini¬ 
mum sway-grace torque which can prevent electric 
release. 

The dependability of the arming unit for low- 
temperature operation has been improved, the initial 
net solenoid thrust available to “arm” the unit has 
been increased, the maximum return spring force 
available to return the plunger from “Armed” to 
“Safe” position has been more than doubled, and the 
maximum coil temperature of solenoid for continu¬ 
ous operation has been reduced from 135-155 C to 
100.5 C. 

The bomb hooks have a hardness of 54-58 Rock¬ 
well C, as compared to 30-42 for the old model, there 
is no tendency to hang up under load after release, 
and the approximate average breaking load for a 
single hook has been decreased. 3 

18 2 3 Development of Mark 54 Mod O 
Bomb Rack' 1 

Procedure 

An independent investigation of the Mark 51 Mod 
7 bomb rack led to a number of modifications. Enclo¬ 
sures were added where possible to protect against 
dirt and ice. Materials were chosen to give the least 
galvanic action. All linkages were analyzed with and 
without friction, and a coefficient of 25 per cent was 
used to provide sufficient margin in all but extreme 
cases. To reduce the effects of seizure, sticking, and 
friction, all parts were pivoted wherever possible and 
rectilinear motion was avoided except in the sole¬ 
noid plunger and compression springs. The design 
was made so that dimensional accuracy would not be 
too important and would have only a minor effect on 
operation. Unit assembly of parts acting together was 
carried out in the two solenoid mechanisms. 

Fhe new rack designed according to these general 
specifications was delivered to the Bureau of Ord¬ 
nance for testing. 

Results 

The design of the new Mark 54 Mod O bomb rack 
is shown in Figure 2. The bomb is held in place by 

<1 This investigation was conducted by the I-T-E Circuit 
Breaker Company, Philadelphia, Pa., under OSRD contract 
OEMsr-1333. 








MANUAL RELEASE CONTROL-\ /- MANUAL ARMING CONTROl 


290 


SPECIAL DEVICES 



-Hrt 


Figure 1. Mark 51 Mod 7 bomb rack (above), with redesigned parts as proposed in Mark 51 Mod 11 bomb rack. 











































BOMB RACKS 


291 


FORWARD 

-m - 


HOOK 


MANUAL 

ARMING 

CONTROL 


MANUAL 

RELEASE 

CONTROL 



NOSE-ARMING 

HOOK TAIL-ARMING 

HOOK 


RELEASE 

MECHANISM 


CHARGING 

MECHANISM 


Figure 2. Mark 54 Mod. O bomb rack. 


two independent hooks on 14-inch centers, locked by 
two dead-center roller latches which are actuated 
by means of a single impact-producing linkage. With 
this design it is possible for one hook to be latched in¬ 
dependently of the other, but if latching is not com¬ 
plete, release of pressure on the bomb-hoisting cable 
will immediately lower the bomb. 

The action to release the bomb consists of moving 
the prop latch from in front of the roller which is on 
the center pin of the force-reducing toggle. The pres¬ 
sure of the release springs causes this toggle to col¬ 
lapse, and after an initial free motion, the hook-lock¬ 
ing latch is struck a hammer blow and moved from in 
front of the hook roller. The hook then has no re¬ 
straint and the weight of the bomb causes it to fall out 
of the rack from any position up to the vertical. To 
facilitate the action in the vertical position, the sides 
of the retaining lugs are sloped 15 degrees, which is 
the angle of 25 per cent friction, so that with no effec¬ 
tive force to rock the bomb out of the rack, the slope 
would tend to let it slide out. This is added insurance 
to make an effective 15-degree slope of the rack when 
it is actually vertical. Since the bomb weight is not 
used to open the release mechanism, the manner of its 
application has no effect on the release action. The 
smoothness of the hook surface is therefore immate¬ 
rial, and any indentation due to softness or brinelling 
as a result of vibration has no effect on the operation. 
The spring required to trip the bomb produces about 


25 times the amount of energy necessary to overcome 
the friction at the roller caused by the weight of the 
bomb and to effect release. 

To improve operation of the arming mechanism, 
the coils are made to occupy the maximum available 
space in order to have the greatest amount of copper 
and largest radiation area. The iron magnet frame 
consists of a single rectangular block with two cavities 
machined in it. It fits snugly between the side walls of 
the rack to which it is bolted and pinned, giving the 
best heat transfer and the maximum rigidity of the 
rack during loading. To obtain enough force for the 
arming, the size of the coil permits the use of No. 33 
Wire, Roevar insulated, without excessive tempera¬ 
ture rise and with sufficient force developed to give 
approximately twice the force of the original rack at 
no greater consumption of current. 

The Mark 54 Mod O rack was expected to perform 
satisfactorily because of (1) greater facility in attach¬ 
ing bombs, (2) greater reliability in release of bombs 
because of a release mechanism which does not de¬ 
pend on bomb weight for source of energy, impact 
action of release springs, and impact action of release 
coil, (3) reduction of corrosion by use of stainless steel, 
(4) provision of a safety factor of 5 for all loads, (5) use 
of dead-center type latches, and (6) more positive arm¬ 
ing action because of the use of pivoted parts and an 
improved coil. 13 In preliminary trials these expecta¬ 
tions appear to have been met. 









292 


SPECIAL DEVICES 


AUTOMATIC THREAD GAGES The Problem 


Summary 

A new type of thread gage has been developed for 
production use. Production models tested in service 
have given up to a 10-fold increase in speed and a 300- 
fold increase in life, and have handled as many as 
300,000 pieces with the original gage parts and with¬ 
out excessive loss of discrimination. 

A bibliography on the manufacture and gaging of 
threads and a monograph on the manufacture of 
thread rings and plug gages have been prepared. 

As a result of this work and its applications in 
industry, a substantial contribution was made to 
the art of gaging threads as well as a considerable 
speed-up in the large-scale production of needed war 
materials. 



Figure 3. Schematic arrangement of roller-type thread 
gage. 



Figure 4. Test model of roller-type thread gage. 


In April 1942, a serious limitation in the produc¬ 
tion of war materials was resulting from a shortage of 
thread gages and especially from a shortage of ring 
gages. Because of their design and the precision re¬ 
quired in their manufacture, mass production was 
practically impossible. The limited number of gages 
produced by tool room methods was unable to cope 
with the daily production of hundreds of millions of 
threaded parts requiring inspection. The situation 
was made even more acute by the fact that the avail¬ 
able type of gage could be used on only a few thou¬ 
sand pieces before its wear became excessive and it 
had to be discarded. 

At the request of the U. S. Army Ordnance Depart¬ 
ment, a project was established to find an immediate, 
practical solution to this problems Suggestions in¬ 
cluded (1) the modification of current designs to per¬ 
mit easy salvage, (2) the development of mass pro¬ 
duction methods for the current designs, (3) the 
perfection of special treatments to protect the surfaces 
of current gages from wear, and (4) the development 
of an entirely new type of gage which could be mass- 
produced or which would contain easily replaceable 
wearing elements or be highly resistant to wear. 

Before this investigation was completed, the Ord¬ 
nance Department undertook to provide temporary 
relief for the gage shortage by giving contracts for 
gage manufacture to small tool shops. It was found, 
however, that few such shops knew the techniques of 
thread gage production and that no adequate infor¬ 
mation was readily available. Accordingly, a simple 
thread gage production manual was requested for use 
by the personnel of these shops. f 

Finally, since no bibliography on thread manufac¬ 
ture and gaging had been published since 1918, a re¬ 
quest was made for the preparation and publication 
of an up-to-date bibliography.* 1 

,8 ' 3 ' 2 Procedure 

The suggested modification of current designs to 
permit easy salvage was discarded with the decision 

e This investigation was conducted by the Bryant Chucking 
Giinder Company, Springfield, Vermont, as subcontractors to 
the Jones and Lamson Machine Company, Springfield, Vermont, 
under OSRD contract OF.Msr-497 as Project OD-49. 

f Preparation of this manual was undertaken by the Jones 
and Lamson Machine Company, Springfield, Vermont. 

s Preparation of this bibliography was undertaken by the 
Jones and Lamson Machine Company, Springfield, Vermont. 



















AUTOMATIC THREAD GAGES 


293 




Figure 5. Schematic arrangement of shoe-type gage for Figure 6 . Schematic arrangement of shoc-t\|>e gage for 

external threads. internal threads. 


that tlie only practical modifications would involve 
the use of replaceable wearing elements or the plating 
and refinishing of worn gages, either of which would 
involve time-consuming precision methods. 

Preliminary considerations showed that no radical 
improvement could be expected by developing mass 
production methods for the current design of gages. 
The manufacture of plug thread gages had already 
been facilitated by the adoption of the thread grinder, 
but this development was proceeding as rapidly as 
could be expected and no other production method 
appeared to offer much promise. 

Investigation revealed a number of potentially use¬ 
ful methods for the treatment of gage parts to increase 
wear resistance. The only one offering considerable 
improvement, however, seemed to be the application 
of a thin, uniform layer of tungsten or other hard 
carbide, and no useful method was available for the 
application of such a layer to the surface of a finished 
gage. 

Major emphasis was therefore placed on the devel¬ 
opment of a new type of gage. Here it was recognized 
immediately that if a thread is to be gaged throughout 
its length, as is necessary to insure assembly, the gage 
must be turned on the thread a number of turns equal 
to the number of threads. The successive threads of 
the gage are consequently subjected to wearing action 
in proportion to their distance from the back end of 
the gage, since each succeeding thread is subject to 
wear over fewer turns, d his results in the tapered or 
“bell-mouthed” wear commonly noted in used ring 
thread gages. 

This bell-mouthed wear could be eliminated if the 
part could be introduced without threading on and 
gaged by only a slight amount of turning needed to 
insure seating and to gage the ftdl circumference. 
This would require only a fractional turn for each 
gaging, reducing the total wear on the gage elements 
and prolonging the life of the device. 


On this basis, consideration was given first to a de¬ 
sign incorporating two threaded rollers mounted on 
fixed parallel axes and one roller on a movable axis 
parallel to the other two (Figure 3). The movable 
roller is mounted at the end of a pivoted arm with the 
pivot axis parallel to the roller axis, the three rollers 
being approximately equally spaced angularly about 
the axis of the work or piece to be gaged. A dial indi¬ 
cator bears on the pivoted arm to indicate its position 
and thereby the deviation in the size of the work. In 
operation, the movable roller is lifted away from the 
fixed rollers and the work introduced between them. 
Then the arm is released, the movable roller bears 
down upon the work, pressing it against the fixed 
rollers, and the dial indicator bears against the arm. 
The dial indicator zero setting is established by in¬ 
serting a master reference workpiece. 

A test model constructed to this design (Figure 4) 
was found to possess several undesirable features. 
With threaded rollers, the phasing of the rollers to 
insure simultaneous seating requires an excessively 
complex mechanism. If simple grooved rollers are 
used, they must be skewed to match the lead angle of 
the thread; furthermore, to insure proper engage¬ 
ment, the rollers must be so short that they cannot 
gage the entire length of thread in one setting. In ad¬ 
dition, there is no wiping action to remove the dirt 
which accumulates on the surface during the gaging 
of dirty or oily parts, and the gaging is not uniformly 
accurate. 

From these observations it was decided that some 
sliding contact must be provided, both to remove dirt 
and to avoid mechanical problems introduced by the 
rollers. The gage was therefore modified by replacing 
the three rollers with three threaded shoes which have 
relatively narrow bearing faces and sharp corners to 
scrape away dirt and which are long enough to engage 
the full length of the thread being gaged. The method 
of gaging by dial indicator bearing on a movable gage 






















294 


SPECIAL DEVICES 





Figure 8. Assembled pilot model gage for female threads. 


Figure 9. Pilot model of manually operated gage for male 
threads. 


element was retained. The flat spring pivot was 
adopted as the best means available for providing a 
frictionless, accurately fixed pivot for limited motion. 
Two arrangements of this design were planned for 
external and internal threads (Figures 5 and 6). 

At the suggestion of the Ordnance Department, ex- 


REED PIVOT 


Figure 7. Gaging element of male-thread gage. 


PIN 


DISENGAGING 

ELEMENT 


FIXED 

SHOES 


MOVABLE 

SHOE 


perimental models were constructed for both male 
and female threads of the 2-inch-12NS-1 thread on a 
component of the M-21 booster (Figure 7). 

In order to make the operation of the gage as nearly 
automatic as possible and to reduce the labor of 
thread gaging, the design was again modified to pro¬ 
vide a movable element which is held open by a 
spring and closed by a solenoid. A microswitch con¬ 
trols the solenoid and is actuated by a small pin be¬ 
tween the fixed shoes. When a workpiece is pressed 
against the fixed shoes, it engages the pin, closes the 
microswitch, and thus operates the solenoid to close 
the gage. Moderate hand pressure against the work¬ 
piece to cock it slightly is sufficient to release the gage. 
This gage was later redesigned (Figure 8) to handle 
the windshield mounting thread on the hardened 
A.P. cap of the 40-mm solid shot, and appeared to 
offer many distinct advantages; however, as a compro¬ 
mise on speed of operation for the sake of reliability, 
the automatic closing and opening feature was elimi¬ 
nated and the final gage for the A.P. cap was con¬ 
structed for hand operation (Figure 9). 


FIXED SHOES 


MOVABLE 

SHOE 


INDICATOR 


GUIDE PINS 


FIXED SHOE 

MOVABLE SHOE 
PIVOT ARM 
MOVABLE ARM 


PIVOT ARM 
































AUTOMATIC THREAD GAGES 


295 


18,33 Results 

The final model was sent into the field for service 
testing by manufacturers of Ordnance equipment on 
their production lines. In the hands of briefly trained, 
competent operators, it was found to be from five to 
ten times as fast as the conventional ring gage. Instead 
of screwing the workpiece into the gage, the operation 
consists of opening the gage by squeezing the lever, 
inserting the part, releasing the lever, and giving a 
half turn to seat and check roundness. The successive 
steps run one into the other in such a manner as to 
constitute what is substantially a single continuous 
operation. 

When work began on this project, the life of a gage 
used on the A.P. cap, which is hardened after machin¬ 
ing and not ground, was limited to the handling of 
about 1,000 pieces. On the same cap, the new gages 
handled 60,000 pieces without noticeable wear of 
gage parts, and some new gages still in service at the 
completion of this study have handled as many as 
300,000 pieces with the original contacting elements. 
The discrimination of the new gages is sufficient to 
meet Ordnance Department requirements, and they 
reveal errors not caught with the standard design of 
ring gage. 10 

Idle bibliography 14 was compiled and 120 copies 



Figure 10. Production model of manually operated gage 
lor male threads. 


distributed, and the manual on gage manufacturing 
methods 15 was written and 500 copies distributed. 

Later the designs were slightly modified for produc¬ 
tion models of the new gages, and by June 15, 1945, 
more than 1,200 units were manufactured and 
shipped. The production models included several 
sizes for manual operation (Figure 10) and one for 
electrical operation (Figure 11). Many of these pro¬ 
duction units have been used on several hundred 
thousand operations without noticeable wear and 
have greatly increased the speed and accuracy of in¬ 
spection. In some cases they have made it possible to 
gage parts which could not be readily inspected by 
the older ring gages. 

18,3,4 Conclusions 

The new gage developed in this investigation was 
designed primarily as a Go gage for male threads to 
take the place of the conventional ring gage. Mating 
parts which pass this new gage will assemble with fits 
which are no tighter than was intended by the de¬ 
signer of the parts. 

When gages wear rapidly, excessive allowances 
must be made for wear. As a consequence, parts 
checked during the early life of the gage fit together 
too loosely and parts gaged during its later life fit too 
tightly. The new gage, however, can be kept in con¬ 
tinuous adjustment by resetting the dial indicator 
against a master plug inserted in the gage. Since the 
wear is slight, the thread form changes slowly and the 



INDICATOR 


Figure 11 . Production model of electrically operated gage 
for male threads. 
















29(1 


SPECIAL DEVICES 


gage can be reset many times without sacrifice of 
accuracy. 

Not only does the new gage serve as a Go gage, but 
it also operates as a Not Go gage in checking pitch 
diameter. It will reject undersized parts where the 
thread form is reasonably true. Pitch errors are re¬ 
jected by an oversize indication, provided the pitch 
diameter is not sufficiently undersize to produce a 
screw which can be assembled. Excessive and short 
pitch both show the same indication. The gage will 
not determine true minimum metal pitch diameter 
with some types of thread form, but in its use on Ord¬ 
nance Department work it was required that occa¬ 
sional checks be made with truncated thread rings to 
insure complete control of minimum metal pitch 
diameter thread conditions. 

The Go gage will not check thread form, but rou¬ 
tine gaging with this type of gage accompanied by 
periodic checks of thread form with an optical, pro¬ 
jection-type comparator for control of tooling will 
maintain all but the most extreme standards of high 
quality. 

For many production purposes, thread form can be 
checked with sufficient accuracy by using two of the 
new gages, the second having relieved threads bearing 
at the pitch line only. This second gage serves the 
same purpose as the standard Not Go ring gage, an 
undersize indication being the basis for rejection. 

Since the new gage is easily calibrated, extreme pre¬ 
cision is not required in its production, and its design 
lends itself to mass production methods. 

PNEUMATIC TIRE SUBSTITUTES" 
Summary 

Of the thousands of substitutes proposed to replace 
pneumatic automobile tires for civilian and military 
service, the twelve most promising were constructed 
and tested. Although none of these twelve had been 
found satisfactory when the project was terminated 
because of the assured success of the synthetic rubber 
program, one of them—the Martin Elastic Spoke tire 

h Project OD-96. 

i This investigation was conducted by the Rudd Wheel Com¬ 
pany of Detroit. Mich., OSRD contract OEMsr-938; Kelsey-Hayes 

W heel Company, Detroit, Mich.. OEMsr-907; Motor Wheel Cor¬ 

poration, Lansing, Mich.; American Steel & Wire Company, 
Cleveland. Ohio, OEMsr-72; Beyer and Tarn of Pittsburgh, Pa., 
OEMsr-568; Dr. Philip Newton of New York, N. Y., OEMsr-631; 

William Allen Brown of Philadelphia, Pa., OEMsr-756; James V. 


—appeared to deserve additional study. Several of the 
Martin tires had been run more than 7,500 miles and 
one more than 10,000 miles over paved and unpaved 
roads at speeds up to 85 mph. 

18 41 The Problem 

In March 1942, when the danger of a rubber short¬ 
age was becoming increasingly acute, the U. S. Army 
Quartermaster Corps and later the Ordnance Depart¬ 
ment asked for a thorough investigation of “the pres¬ 
ent development and patents covering devices that 
would eliminate the use of rubber tires, and recom¬ 
mendations as to possibilities of further develop¬ 
ment.” * 1 

This problem was one which had been given much 
thought and study, particularly during the last war 
and at times of high rubber prices, and thousands of 
patents and suggestions had been submitted for con¬ 
sideration. It appeared at the outset that the complete 
elimination of natural or synthetic rubber was impos¬ 
sible and that the goal should be the use of as little 
rubber as possible. 

In the search for a tire or complete wheel which 
could be used on present automotive vehicles, maxi¬ 
mum life, minimum use of critical material, and ease 
of manufacturing were considered of paramount im¬ 
portance. The static load deflection of the substitute 
tire was to approach that of the pneumatic. The total 
weight and particularly the wheel unsprung weight 
(that portion of the weight of the wheel lying between 
the springs of the wheel and the ground) were both to 
be kept to a minimum. The tread area in contact with 
the road was, if possible, to equal that of the pneu¬ 
matic tire. 

18 - 4 - 2 * Procedure 

Between March 1942 and October 1943, when work 
was discontinued, 12 wheels (5 non-resilient and 7 re¬ 
silient) were built with both private and government 
funds, and examined at Camp Holabird, Fort Knox, 
and other military establishments. 21 Those which in- 


Martin of Rochelle Park, N. J.; James Mathew MacLean of 
Amick and Spicer, Detroit, Mich., OEMsr-757; William E. Joor 
of Houston, Tex., OEMsr-758; Factory Products Company of 
Dearborn, Mich., OEMsr-736; Ampat Corporation, New York, 
N. Y., OEMsr-775; under supervision of Division 12. OSRD, and 
in coordination with the Resilient Wheel Committee, represent¬ 
ing the U. S. Army, and the wheel and tire industry. 







PNEUMATIC TIRE SUBSTITUTES 


297 



Figure 12. Non-resilient substitute tires: Grasso (upper left), Atlas-Habberstadt (upper right), Knox (lower left), 
and Goodyear (lower right). The Budd is not shown here. 


dicated any promise were placed on vehicles and run 
over paved road sections at different speeds, given 
cornering tests, and then run around test courses until 
failure occurred. In the case of the Martin Elastic 
Spoke tire, additional laboratory tests were performed 
to determine some of its operating characteristics.i 

1843 Results 

Non-resilient Substitutes 

Five possible substitutes (Figure 12) for a spare tire, 
all rigid and non-resilient, were investigated with the 
thought that, if the rubber shortage became ex¬ 
tremely critical, something of this type might serve 


in an emergency in place of the normal fifth or spare 
tire. 

I’lie Atlas-Habberstadt tire is a wooden tire 
mounted in place of the pneumatic, the Budd wheel 
is a pressed steel disk with a rubber tread member, the 
Goodyear tire is a Thiokol-impregnated cotton fabric 
tread material mounted in place of the regular pneu¬ 
matic, the Knox tire uses a brake block material as a 
tread member in place of the pneumatic tire, and the 
Grasso wheel is a thin disk designed to be placed out¬ 
side the pneumatic tire and to carry the weight of the 


j These tests were conducted by the Vibration Fatigue Labo¬ 
ratory of the American Steel & Wire Company, Cleveland, Ohio. 


















298 


SPECIAL DEVICES 


vehicle in case the pneumatic tire is damaged. Since 
they are rigid, these five types transfer all of the road 
shock to bearing and axle structures and other vehicle 
parts, and they can be used only for emergency pur¬ 
poses for very limited mileage and at low speed. All 
but the Grasso wheel were discarded without any 
mileage tests, for it was recognized that their life 
would be relatively short. The Grasso wheels failed at 
20 miles on the test course, at moderate speeds. 

Resilient Substitutes 

Seven types of resilient substitutes (Figure 13) were 
tested and in some cases modified and retested where 
this was possible. Their general characteristics are 
given in Table 1. 

In preliminary tests on the Am pat wheel, failure 
began within 10 miles. Modifications were attempted 
but did not significantly improve performance. 

The Beyer and Tarn tire was exceptionally heavy, 
its unsprung weight very high, and it failed after some 
50 miles of driving over paved roads and around the 
test course. 

In early tests, the Brown tire k was reported by the 
inventor to survive approximately 500 miles of driv- 


)' Data on this tire are not available since its construction was 
not completed until after termination of work on the project. 


ing. After attempted improvement and simplifica¬ 
tion, however, it failed after some 300 miles. 

Th eBudd tire showed considerable resiliency when 
used over paved roads at speeds less than 30 mph but 
failed under more severe tests at about 400 miles. 

A car equipped with the Joor tire drove fairly well 
over the test course, but the tire failed within 30 
miles. 

The MacLean tire, similar in construction to many 
resilient streetcar wheels, failed after relatively low 
mileage, principally because the wheel had been con¬ 
structed from castings which cracked. Had pressed 
disks similar to standard automotive wheels been 
used, it is believed more satisfactory results would 
have been obtained. 

The Martin Elastic Spoke tire (Figure 14) appeared 
to be the most promising of all types tested. It uses the 
standard wheel with a portion of the rim cut off. Re¬ 
siliency is obtained through a series of radial elastic 
spokes and three semi Hex ible hickory hoops compris¬ 
ing the tread rim. A rubber or synthetic tread cover is 
vulcanized and bonded to these hoops. Hickory pins 
connect the elastic spokes to both the wheel and the 
tread rim. The spokes are assembled prestressed in 
tension. The spokes at the portion of the wheel where 
the load is applied are partially relaxed or under com¬ 
pression, depending on the load or force applied, and 


Table 1. Comparative Characteristics of 6-Ply Pneumatic Tire and Proposed Resilient Substitutes. 


Tire 

Weight 
in pounds 
(incl. wheel) 

Wheel 
unsprung 
weight 
in pounds 
(approx.) 

Resilient member 

T read 

Static load 
deflection in inches 
1,000 1b 2,000 1b 

Pneumatic tire .... 

63 

\i binary 

Air and rubber 

Rubber 

0.67 

1.25* 

Ampat Tvpe A . . . 

. . 87 

68 

Cantilever spring 

Rubber 

0.45 

0.70 

Ampat Type B . 

. . 117 

96 

Cantilever leaf springs 

Goodyear 

(impregnated 

fabric) 

0.40 

0.65 

Bever and Tarn. 151 

Brown (data not available) 

108 

Coiled spring annulus 

Rubber 

0.03 

0.06 

Budd. 

122 

52 

Radial coiled springs 

Rubber 

0.65 


Joor. 

. . 105 

45 

Steel strip S-shaped 

Rubber 

0.20 

0.35 

MacLean (12 units) . . 

. . 108t 

55 

Rubber pads 

Rubber 

0.16 

0.28 

MacLean ( 6 units) . . 

. . loot 

55 

Rubber pads 

Rubber 

0.30 

0.50+ 

Martin—Type A . . . 

• • 42t/£ 

24 

Steel leaf and coiled spring 

Rubber 

1.00 


Martin—Type B 

• • 47l /2 

28 

Helical leaf spring 

Rubber 

0.70 


Martin—Type C . . . 

. . 41 

26 

Rubber-covered hickory hoops 

Rubber 

0.30 


Martin Elastic Spoke . 

. . 48 

23 

Rubber spoke 

Rubber 

0.60 

1.6 


* 35 psi air pressure. At 30 psi, deflections are 0.75 and 1.42" respectively, 
t Based on aluminum construction. For steel, approximately 125 lb. 

{ This was maximum deflection available for this wheel. 























299 


PNEUMATIC TIRE SUBSTITUTES 



Figure 13. Resilient substitute tires: MacLean (top left). Brown (top right), Joor (middle left), Beyer and Tarn (middle 
right), Budd (bottom left), and Ampat (bottom right). 






















SPECIAL DEVICES 


300 



Figure 14. Army jeep equipped with Martin elastic spoke tires. 


the load on the tire is distributed among approxi¬ 
mately two-thirds of the spokes. The static deflection 
closely approaches that of the pneumatic tire. 

Three of these tires survived 7,500 miles without 
failure, and one was still serviceable after 10,000 miles 
(see Table 2). Tread wear measured on one of the 
tires showed a loss of about %4 inch of rubber at 

Table 2. Martin Elastic Spoke Tire Mileage. 


Tires which Tires still 

Miles driven failed serviceable 


0-100. 6 

101-1,000 10 3 

1,001-2,000 . 6 3 

2,001-3,000 . 3 5 

3,001-4,000 . 2 

4.001-5,000 . 

5,001-7,500 . 4 

7,501-10,000 . 3 

10,001-15.000 . 1 


30 16 


5,000 miles and about % 2 inch at 9,000. At slow 
speeds and over brick and gravel, the riding qualities 
were found to be less satisfactory than with pneu¬ 
matic tires, but at speeds more than 30 miles per hour 
there is little noticeable difference. After 30 miles of 


driving at 70 mph, temperature in the center tread 
hoops was found to be only 12 degrees above atmos¬ 
pheric. The tires survived speeds up to 85 mph. Tires 
deliberately damaged by machine-gun fire continued 
to function, even with 50 per cent of the parts dam¬ 
aged and ineffective. 

In order to reduce the amount of rubber in the 
tire, an investigation was conducted on the use of 
Neoprene in place of rubber in the spokes. It ap¬ 
peared that a Neoprene spoke could be used satisfac¬ 
torily. 18 Three other modifications aimed at saving 
rubber (Martin Types A, B, and C) were constructed 
but not subjected to field tests before this project was 
terminated. 

184-4 Conclusions 

At the end of the project, none of the substitute 
tires or wheels was ready for complete and compre¬ 
hensive tests. All except the Martin Wheel depend on 
some form of steel spring mechanism for their resili¬ 
ency, and it appears from the limited tests conducted 
with them that if anything approaching adequate re¬ 
siliency were to be obtained, their life would be very 
limited. Even when used primarily on paved roads 
and at reduced speed, they would probably not sur- 


COISL 






























EMERGENCY RESCUE EQUIPMENT 


301 


vive one or two thousand miles. They are further 
handicapped by high weight, high unsprung weight, 
and failure to absorb damaging vibrations. 

The Martin type tire was found in this study to be. 
the most satisfactory and the one requiring the least 
developmental work before it could be put into lim¬ 
ited production. Although it contains nearly as much 
rubber as does the pneumatic tire and thus does not 
conform strictly to the requirements, it is believed 
that this rubber can be successfully replaced by syn¬ 
thetic or other substitutes. 

While no mechanical design is likely to possess all 
the advantages of a pneumatic tire, it is considered 
likely that a vigorous engineering program cotdd pro¬ 
duce an acceptable emergency substitute, perhaps 
based on the Martin, Ampat, Budd, or MacLean con¬ 
structions. 

'85 EMERGENCY RESCUE EQUIPMENT 
i8.5.t Seven-Man Sailing Boat 1 

Summary 

A seven-man pneumatic life raft designed to be car¬ 
ried by aircraft has been developed and tested. One of 
its principal new features is that it is designed to be 
sailed. This feature is incorporated not so much to 
permit covering of distance as to reduce the likeli¬ 
hood of seasickness, both by casing the motion and by 
giving at least some of the crew something to do. 
Other features are great beam and high sides, together 
with small bulk made possible by a twin-tube con¬ 
struction which provides increased floor space, addi¬ 
tional freeboard, and protection from wind. An in¬ 
flatable double bottom protects occupants from the 
cold. 

The new raft is believed to represent a decided im¬ 
provement over existing models by providing maxi¬ 
mum comfort for the crew, protection against sun 
and rain, camouflage protection against air attack, 
and small bulk in stowage. It can be sailed by inex¬ 
perienced personnel. 

The Problem 

At the request of the Committee on Emergency 
Rescue Equipment of the Joint Chiefs of Staff and 

i Project NE-102. 


the U. S. Navy Coordinator of Research and Develop¬ 
ment, an investigation was undertaken in September 
1943 on a new airborne pneumatic life raft." 1 The 
available type of raft, the Coordinator stated, was 
inadequate for the use intended. Specifications for 
the new type called for (1) maximum comfort for the 
crew, enabling them to live and sleep many days 
aboard the raft, (2) accommodations for the maxi¬ 
mum number of persons and the maximum amount 
of emergency supplies and equipment for the least 
weight and size of the raft, (3) provisions for sailing, 
and (4) dimensions allowing it to fit into the space 
currently allocated aboard planes. 

These requirements indicated that an entirely new 
raft design was necessary. 

Procedure 

Experiments were started with a standard Navy 
Mark VII raft to determine the best types of mast, 
rig, and lateral plane area. Pneumatic fabric lee- 
boards were fastened to the raft tube and a fabric 
fin was placed on the bottom of the raft on its center 
line. The pneumatic leeboards were filled with water 
and supplemented with air from a hand pump. The 
fin was stiffened by two oar blades and was con¬ 
structed so that it could be turned inside out and 
placed inside the raft during tests of the leeboards. 
An A-frame mast was mounted on the raft, set in two 
sockets attached to the main tube, and stays extended 
from a masthead Y-fitting to the bow and stern. A 
single triangular sail was used. 

Tests on this preliminary model showed that the 
leeboards offer considerable stability, but that the 
raft is sluggish to maneuver, uncomfortable for 
seven men, and requires too much space in propor¬ 
tion to its size. The leeboards were removed and a 
fin keel used. This provided considerable improve¬ 
ment in maneuverability. 

Based upon the results of these early trials, a new 
type of raft was designed, and a double tube was 
adopted in place of the usual single tube in order 
to provide more usable floor area, greater freeboard, 
increased stability, and protection against spray, and 
to make possible a smaller main tube which could 
be used as a headrest. Instead of a double or A mast, 
a single mast was used to simplify rigging and han- 

m This investigation was conducted by Sparkman & Stephens, 
Inc., New York, N. Y., in cooperation with the B. F. Goodrich 
Company, Akron, Ohio. 










302 


SPECIAL DEVICES 



Figure 15. Construction of seven-man pneumatic life raft. 































































































































EMERGENCY RESCUE EQUIPMENT 



303 


dling the sails, to reduce needed storage, and to pro¬ 
vide suitable stiffening to the web keel. A double-sail 
plan was adopted in preference to a single-sail plan 
in order to use a shorter mast and thereby lower the 
center of gravity, to increase raft stability, to simplify 
rigging and handling in rough weather, and to make 
it possible to locate the mast where it would be suita¬ 
ble for stiffening the keel. Instead of the built-in type, 
a separate inflatable floor was chosen because it can 
be removed for repairs, used as a life preserver, and 
raised during bailing and sponging the raft bottom, 
and because it will help keep the occupants reason¬ 
ably dry. A fin keel was used in preference to the lee- 
boards because it enables the raft to sail faster, be 
more easily maneuvered, and occupy less packaging 
space. 

Result 

The new raft (Figures 15, 16, and 17) consists of 
one 12-inch diameter main tube surmounted by one 
8-inch diameter tube at an angle of 30 degrees out¬ 
board; a 9-inch diameter pneumatic tube thwart lo¬ 
cated just forward of the raft center; a fabric bottom; 
a fabric keel with a mast socket at the forward end 
to receive the mast; two separate inflatable compart- 


Figure 1(3. Side view of seven-man raft. 


Figure 17. Top view of seven-man raft, showing double¬ 
tube construction. 


mented floor mattresses; a telescopic, six-section, 
aluminum mast extensible to 16 feet, with wire rig¬ 
ging and fittings attached; one suit of sails consisting 
of a jib and mainsail with halyards and sheets at¬ 
tached; complete accessories located in three water¬ 
proof containers; a combination camouflage cover, 
awning, and rain-catcher; a sea anchor; a removable 
folding aluminum and fabric rudder; and a rope 
boarding ladder. T he rudder and the sea anchor are 
both permanently attached to the raft, and spray 
clothes are permanently attached fore and aft to 
the raft tubes. 

Fhe 12-inch main tube is automatically inflated by 
pulling the release of a bottle of carbon dioxide 
which is attached to the stern of the raft and contains 
23/£ pounds of the gas. The 8-inch upper tube, the 
tube thwart, and the inflatable floor bottoms are in¬ 
flated by means of a manually operated hand pump. 

















304 


SPECIAL DEVICES 


These could be constructed to inflate automatically 
with the main tube. 

Corresponding colors are used for each sail and its 
raft attachments. 

The complete raft, including rigging and all ac¬ 
cessories, can be rolled to fit into a standard raft case 
19 inches in diameter and 36 inches long. The raft 
alone, including the keel and inflatable floor, weighs 
58i/2 pounds and provides a floor area of 34.6 square 
feet, in contrast to approximately 61 pounds and 14.6 
square feet, respectively, for the Navy Mark VII raft. 

Conclusions 

The raft as finally built and given preliminary 
tests under both Army and Navy observation 22 ap¬ 
pears to represent a decided improvement over exist¬ 
ing types (Figure 18). All tests indicated that seven 
men can be adequately accommodated in safety and 
comfort. The inflatable double bottom definitely 
protects them from cold water temperatures. The 
twin-tube feature provides increased comfort and 
protection. The combination awning, camouflage 
cover, and rain-catcher is waterproof and affords ade¬ 
quate protection against rain, snow, wind, sun, and 
night dampness, as well as a means of catching rain 
water for drinking, and offers some protection against 
enemy detection. 

In moderate bree/es, the raft can make progress to 
windward, although in strong or light breezes this 
would depend largely on the skill of the helmsman. 
Across the wind or downwind, the raft goes well. In 
general, the sail, centerboard, and rudder equipment 
give satisfactory control over the raft, so that if the 
crew want to stay in one position (the last known 
position is usually that at which survivors are most 
likely to be picked up), it is possible for them to do so. 

The stability is satisfactory. If capsized, the raft 
can be righted by one man. 

For complete evaluation, the new raft should be 
tested under actual sea conditions with typical 
bomber crews fully dressed in heavy flying clothing. 

185-2 Airborne Lifeboat" 

General specifications have been developed for a 
motor lifeboat which can accommodate seven to ten 
men and which can be carried on the underside of 

n Project NE-101. 



Figure 18. Seven-man raft under way in calm sea. 


an airplane fuselage and dropped by parachute to 
men cast adrift from ditched planes. 

For such a boat which could be carried by a plane 
similar to the B-17 Flying Fortress, it was recom¬ 
mended" that the lifeboat should weigh 3,000 pounds, 
the hull alone (including slings and buoyancy chamb¬ 
ers) weighing between 800 and 900 pounds. The 
motor should be similar to the Austin Marine, with 
a weight of 210 pounds plus 30 pounds for miscellane¬ 
ous items. 

Two parachutes would be required, each 96 feet 
in diameter and together weighing 500 pounds. 

I he center of gravity of the lifeboat should be for¬ 
ward of the midship section, and, when slung into 
position on the plane, should be at the center of 
gravity of the plane. The bow of the lifeboat should 
not be too far forward, since otherwise there would 
be a possibility of the boat’s scraping the bottom of 
the plane fuselage when released. 

Provisions and supplies should be included for ten 
men and enough gasoline supplied for approximately 
400 miles of operation. 

When it was learned that the Army Air Forces were 
independently designing their own airborne lifeboat, 
this project was discontinued and no test model was 
constructed. 23 

0 This investigation was conducted by Sparkman & Stephens, 
Inc., New York. N. Y., under OSRD contract OEMsr-154. 










RAIN REPELLENT COATINGS 


305 


I8(i RAIN-REPELLENT COATINGS' 
Summary 

A group of new rain-repellent coatings has been 
developed to improve visibility through rain-covered 
windshields. Although none of these films provides 
prolonged protection, some are effective for periods 
up to 300 minutes in conditions simulating moderate 
to heavy rainfall. 

In some cases, these coatings may be renewed by 
rubbing even after they have apparently lost their 
activity. Of special significance arc forms devised to 
permit application during rain. 

In the course of this study, the properties of more 
than 50 substances were investigated, all of them pre¬ 
pared in mixtures with wax as the essential rain-re¬ 
pellent ingredient. They include various soaps, 
organo-tin compounds, nitrogenous bases, silicones, 
plastics, lacquers, and commercial rain-repellent 
products. The most promising combinations appear 
to be zinc palmitate and wax; tri-octyl silicone and 
wax; tetra-octyl tin and wax; shellac and wax; and 
zinc palmitate, wax, and isoquinoline. 

18 6 1 The Problem 

The impairment of visibility produced by rain or 
spray on a windshield or other optical surface has 
particular significance in military operations, espe¬ 
cially with aircraft and with special sighting instru¬ 
ments which cannot be equipped with mechanical 
windshield wipers. 

In order to control this blinding effect, chemicals 
were needed to provide an effective rain-repellent 
film or coating to be applied to the exposed surface. 
To be most useful, such a coating must be easy to 
prepare and apply, hard enough to withstand normal 
handling, free from undesirable optical effects, and 
able to remain effective after long exposure to rain. 

Two broad classes of vision surfaces were consid¬ 
ered—those of glass and those of transparent plastics. 
When rain strikes either type, the phenomena are 
much the same. If the surface is scrupulously clean, 
the water will spread (the angle of contact between 
glass, water, and air being zero degrees in magnitude) 

i> Project AC-19. 

This investigation was conducted by the National Research 
Corporation, Boston, Mass., under OSRD contract OEMsr-436. 


and tend to drain as a continuous sheet or film of 
water. A surface which has been exposed to the atmos¬ 
phere for some time, however, is usually not clean 
and usually not completely wetted by water. When 
rain falls on an inclined surface of this sort, the water 
settles as flat, irregular drops, drainage takes place 
along twisting paths or channels, and these relatively 
massive bodies of water cause obstruction and distor¬ 
tion of vision. 

One method to improve vision is to modify the 
surface with a wetting agent which would lower the 
surface tension and spread the water in a thin, uni¬ 
form, transparent film. Since wetting agents by defi¬ 
nition are soluble in water, any coating made with 
such substances would be quickly dissolved and re¬ 
moved. 

A more practical method is to modify the surface 
with a luater-repellent coating which woidcl give a 
large angle of contact between coating, water, and 
air, and cause the water to be shed in discrete droplets 
so small that they would not interfere with vision. 

As a water repellent, no compound was readily 
available to equal paraffin wax in giving a high con¬ 
tact angle between coating, water, and air, and a low 
solubility in rain. Thus, it appeared at the outset that 
a paraffin wax coating possesses at least some of the 
required characteristics, but unfortunately it has by 
itself little or no affinity for glass. An investigation 
was therefore initiated by NDRG to find materials 
which, in one way or another, can give a firm adhesive 
bond between glass and a wax coating.'i 

1862 Procedure 

Materials 

A number of paraffin icaxes were studied, with the 
most suitable being a semi-micro crystalline wax 
melting at 52 C. Others, with melting points from 62 
to 67 G, were found less satisfactory. 

As mixing materials which themselves possessed 
at least some degree of water repellency and of af¬ 
finity for glass, various soaps were prepared and 
tested. r In the absence of wax, none of them is easily 
applied to glass. A series of paste-like mixtures was 
then made, each composed of paraffin wax, one of 

r Aluminum stearate, calcium stearate, cobalt stearate, ferric 
stearate, lead stearate, zinc stearate, aluminum palmitate, cobalt 
palmitate, zinc palmitate, aluminum resinate, cobalt resinate. 
lead resinate, zinc resinate, aluminum oleate, copper oleate. lead 
oleate, lead naphthenate, and zinc naphthenate. 








306 


SPECIAL DEVICES 


these soaps, and a suitable solvent, and of these, a 
zinc palmitate mixture was selected as the most 
suitable for further tests. 

It was felt that certain organo-metallic compounds 
might have value, and several tetra-alkyl tin com¬ 
pounds were selected because of their relatively low 
toxicity and flammability. 8 Tetra-ethyl tin, tetra-octyl 
tin, and tetra-acetyl tin appeared to be most promis¬ 
ing and were studied in more detail. 

Nitrogenous bases had been recommended, and 

o 

several of these were prepared.* Without wax, none 
of these can be applied satisfactorily to glass surfaces, 
and even with wax only two appeared to be useful. 
Meso-methyl tetra-methyl benzimidazole gives a film 
which can be applied to glass, but since this material 
is not readily available and since it gives a film no 
better than others obtained more easily, it was not 
considered further. Isoquinoline was studied in spe¬ 
cial mixtures with zinc palmitate and wax to give 
rain-repellent coatings which can be applied to wet 
surfaces. 

Twelve different silicone mixtures were synthe¬ 
sized, giving a series of films with properties depend¬ 
ing upon the predominant monomer in each product 
and upon the temperature at which it is prepared." 
When applied directly to glass, all of these materials 
give films which are extremely perishable; they repel 
rain for only a few moments and then flood com¬ 
pletely. When mixed with wax, however, nine of the 
silicones give more permanent films, and these com¬ 
pounds—the ethyl, amyl, tri-amyl, tri-octyl, tri-decyl, 
phenyl, di-phenyl, tri-phenyl, and tetra-phenyl sili¬ 
cones—were investigated further. 

Finally, investigations were conducted on a num¬ 
ber of commercially available plastics’^ and a com¬ 
mercial rain-repellent compound, the Lorr Rain 
Repeller, which is apparently a quick-drying lacquer 
substance containing wax. None of the plastics ap¬ 
peared to be useful directly, giving either highly 

s Tetra-ethyl tin, tetra-isoamyl tin, tetra-octyl tin, tetra-acetyl 
tin, tetra-ethyl tin chloride, and tetra-ethyl tin fluoride. 

t Castoramine hydrochloride, tri-methyl benzyl ammonium 
stearate, stearyl tri-methyl ammonium bromide, lauryl pyridin- 
ium chloride, isoquinoline, and meso-methyl tetra-methyl ben¬ 
zimidazole. 

u Ethyl silicone, di-ethyl silicone, amyl silicone, tri-amyl sili¬ 
cone, di-octyl silicone, tri-octyl silicone, tri-decyl silicone, phenyl 
silicone, di-phenyl silicone, tri-phenyl silicone, tetra-phenyl sili¬ 
cone, and tri-naphthyl silicone. 

v Monomeric methyl methacrylate, Lucite, Plexiglas, “Boil- 
able Lucite,” cellulose acetate, polystyrene, polyethylene, and 
various "Vinylites.” 


perishable films when used alone or marked by poor 
optical qualities when mixed with wax, and all were 
discarded except Plexiglas and several “Vinylites ’ 
which were used in special applications. 

Application 

The compounds selected above were applied in 
one of two forms to give a repellent coating: (1) mixed 
with wax and, if necessary, a suitable solvent, and 
applied directly to the surface; (2) polymerized or 
deposited from a solution on the surface, alone or 
with wax, and baked if necessary to give a subcoat 
to which paraffin wax was applied later as a top 
coat. 

In addition, special combinations of zinc palmi¬ 
tate, wax, and isoquinoline were prepared in benzene 
and carbon tetrachloride for use on wet glass, and 
were applied by spray gun. 

T ESTS 

Preliminary measurements were made of the con¬ 
tact angle between each coating, air, and water, and 
of the tilt angle, or angle at which surfaces must be 
tilted for drops of certain sizes to roll off them. 


Table 3. Durability Tests on Wax Mixture Coatings. 

(Each compound listed here was applied in a mixture 
with paraffin wax and exposed in a rain machine.) 


Compound 

Surface 

coated 

Rain 
(inches 
per hr) 

Wind 

(mph) 

First Start 
signs of of 
distortion flood, 
(minutes) (min.) 

Zinc palmitate 

Glass 

25 

12-20 

25 

55 

Zinc palmitate 

Plexigl 

as 25 

12-20 

40 

85 

Tetra-ethyl tin 

Glass 

25 

12-20 

40 

55 

Tetra-acetyl tin 

Glass 

25 

12-20 

40 

55 

Tetra-octyl tin 

Glass 

25 

12-20 

60 

85 

Ethyl silicone 

Glass 

25 

12-20 

25 

30 

T ri-amyl silicone 

Glass 

25 

12-20 

85 

— 

Tri-decyl silicone 
Tetra-phenyl 

Glass 

25 

12-20 

85 

115 

silicone 

"Vinylite” 

Glass 

25 

12-20 

45 

75 

copolymer 

Glass 

25 

12-20 

0 

0 

Shellac 

Glass 

25 

12-20 

0 

- 


The ability of the different coatings to withstand 
rain was measured in rain machines which could give 
any desired degree of rainfall at any desired wind 
velocity. In most cases, records were made of the 
times when each coating first showed distortion of 
the drops on its surface, when flooding began, and 
when vision was definitely interrupted. 


CXENTmigFPrtr. 









RAIN-REPELLENT COATINGS 


307 



Figure 19. Effect of anti-rain compound 2-A, composed of zinc palmitate and wax. (A) model airplane viewed through 
dry glass plate, no wind or rain; (B) same airplane viewed through non-coated glass plate, rain 22 inches per hour, 
wind velocity 20 mph; (C) same airplane viewed through glass plate coated with anti-rain compound 2-A, rain 22 inches 
per hour, wind velocity approximately 20 mph. 


,8 - 6-3 Results 

Dry Application 

Table 3 gives the results on the first group of se¬ 
lected compounds applied in mixtures with wax and, 
if necessary, a suitable solvent. Zinc palmitate was 
found to give improved vision when first applied 
(Figure 19) but almost complete flooding in about 
145 minutes on either glass or Plexiglas. Its coatings 
can be revived by rubbing. When they do break 
down, the degradation is marked by a rapid coales¬ 
cence of drops giving channels of water, followed by 
a quite rapid coalescence giving solid floods of water 
which completely distort visibility (Type A break¬ 
down). 

The three alkyl-tin coatings give almost complete 
flooding in about 145 to 240 minutes. These coatings 
can also be revived by rubbing. With these films, de¬ 
gradation is marked by a slow coalescence of large 
drops giving channels and floods, and vision is badly 
impaired both by drop size and by fogging {Type B 
breakdown). 

Ethyl silicone coatings are almost completely 
flooded in about 70 minutes, with a Type A break¬ 
down and the film stripped from the glass. The 
other silicone coatings tested are flooded more slowly, 
with a Type B breakdown and vision generally poor 
after 130 minutes. 

Both the “Vinylite” copolymer and the shellac 
coatings break down almost immediately, with the 
“Vinylite” film lifted completely from the glass in a 
few seconds. 

Table 4 shows the results with the compounds ap¬ 
plied as a subcoat and then covered with wax. Tri¬ 
octyl silicone, shellac, and “Vinylite” subcoats are 
only about one-fourth flooded in 165 minutes. The 
test on Plexiglas shows that this glass substitute acts 


as its own subcoat, holding a wax top coat which is 
less than one-fourth flooded in 270 minutes. 

Further tests revealed that the best of these coat¬ 
ings are unable to withstand extremely heavy rain¬ 
fall, all of them beginning to break down at about 30 
minutes under 25 inches of rain per hour with serious 
impairment of vision at about 60 to 80 minutes. Un¬ 
der more moderate rainfall—about 4.5 to 5.0 inches 
per hour—the best coatings give unimpaired vision 
for 300 minutes or more. Increasing the wind velocity 
from 25 to 65 miles per hour has no serious effect. 

Table 4. Durability Tests on Subcoats. 

(Each compound listed here was applied to glass as a 
subcoat, then covered with a top coat of paraffin wax, 
and exposed in a rain machine.) 


Subcoat 

Top 

coat 

Rain 
(inches 
per hr) 

Wind 

(mph) 

First 
signs of 
distortion 
(minutes) 

Start 

of 

flood. 

(min.) 

Ethyl silicone 
plus wax 

Wax 

25 

15-20 

30-00 

55-75 

Amyl silicone 

Wax 

25 

15-20 

25 

40 

Amyl silicone 
plus wax 

Wax 

25 

15-20 

40 

55 

Tri-octyl silicone 

Wax 

25 

15-20 

85 

— 

Phenyl silicone 

Wax 

25 

15-20 

40 

55 

Di-phenyl silicone 

Wax 

25 

15-20 

25 

10 

Tri-phenyl silicone 

Wax 

25 

15-20 

50 

70 

Shellac plus wax 

Wax 

25 

15-20 

90 

— 

Vinylite VYNS 
resin plus wax 

AVax 

25 

15-20 

85 


Plexiglas 

Wax 

25 

15-20 

120 

185 


Wet Application 

The mixtures of zinc palmitate, wax, and isoquino¬ 
line developed for application to wet surfaces were 
found to give coatings as effective as those obtained 
with zinc palmitate and wax applied to a dry surface. 





















SPECIAL DEVICES 


.‘>08 


One of these isoquinoline preparations may be ap¬ 
plied with a pressure spray gun to a wet surface, 
whereupon it flows out in a thin, quick-drying film 
which, without rubbing, becomes perfectly clear and 
highly repellent, remaining active under 25 inches of 
rain per hour for more than 40 minutes. Successive 
coatings may be applied. The film may be completely 
removed by spraying lightly with carbon tetra¬ 
chloride. 

1864 Conclusions 

The best new combinations developed during this 
research are zinc palmitate and wax ( Anti-liain 
Compound , Experimental Type 2-A); shellac and 
wax, applied as a subcoat and then covered with a 
wax top coat ( Anti-Rain Compound, Experimental 
Type 2-C ); zinc palmitate, wax, isoquinoline, ben¬ 
zene, and carbon tetrachloride ( Anti-Rain Com¬ 
pound, Experimental Types 2-D and 2-E ), applied 
to wet surfaces; tetra-octyl tin and wax; and tri-octyl 
silicone, applied as a subcoat and then covered with 
a wax coat. Although these may be surpassed in dura¬ 
bility by other compounds, they possess the best 
combination of availability, ease of application, ease 
of renewal, and durability. 30 

None of the materials tested or developed in this 
study possesses any permanent value. It is significant, 
however, that occasional light wiping across a surface 
coated with these compounds will prolong the useful 
life of the coating, perhaps to as much as 8 hours. It is 
felt that a windshield wiper might be profitably used 
in conjunction with such coatings. 

The action of quinoline is apparently due to its 
ability to displace the film of water and carry the 
wax and zinc palmitate to the glass surface, where 
they are precipitated in place. A lower concentration 
of quinoline ( Type 2-D) appears to be most useful 
for application to stationary objects, while mixtures 
with higher concentration ( Type 2-E) may be useful 
for application to the windshields of airplanes while 
in flight through rain. 

It appears that the development of a permanently 
rain-repellent surface is remote, but useful temporary 
coatings may be devised for aircraft. It does not ap¬ 
pear that coatings with higher angle of contact will be 
readily found. 

1865 Recommendations 

Jet systems to spray films of rain-repellent materials 
over the windshield should be developed particularly 


for airplanes. Further investigations arc indicated, 
particularly on zinc palmitate-wax systems. Testing 
by military air services and commercial air lines 
in cooperation with a competent jet manufacturer 
should solve the problem of vision through an air¬ 
plane windshield during a heavy rain storm. 

18.7 ANTI-FOGGING METHODS 

Summary 

Anti-fogging compounds incorporating wetting 
agents as the active ingredients have been developed 
and found effective in improving the quality of vision 
through transparent surfaces. Their beneficial effect, 
however, is only temporary. 

l he fogging of some optical instruments, such as 
the Mark 111-7 telescopic sight in use by naval dive 
bombers in 1942, can be avoided by the use of desic¬ 
cating devices. 

I he most satisfactory way to prevent fogging of 
windshields is the use of internal heaters and de¬ 
frosters. 

18,7,1 The Problem 

A common cause of impairment of visibility 
through vision devices is the fogging or misting which 
occurs when moisture condenses on the vision sur¬ 
faces as very small, discrete droplets of water which re¬ 
fract the light rays coming through the surface and 
give a frosted appearance on the surface of the glass. 
This phenomenon occurs on the windshields of air¬ 
craft, water craft, and land vehicles, and on the lens 
elements of goggles, telescopes, periscopes, and simi¬ 
lar devices, and in some circumstances may be severe 
enough to make an instrument practically opaque 
and useless. 

A need for some means to control this fogging had 
been expressed particularly by the pilots of Navy 
dive bombers in the Southwest Pacific, who found 
their telescopic sights becoming heavily fogged du¬ 
ring diving operations, and by representatives of the 
U. S. Army Tank Automotive Center, Detroit. With 
the belief that no single method would be generally 
applicable to all conditions of fogging, a study was 
begun on three possible methods:'! (1) the applica¬ 
tion of a wetting agent which would cause the mois¬ 
ture to spread over the surface in a thin, uniform film 
offering only slight impairment to vision, (2) the ap¬ 
plication of a moisture-absorbing coating, and (3) 








ANTI-FOGGING METHODS 


309 


the use of a device to desiccate the atmosphere sur¬ 
rounding the vision surface. w 

The effectiveness of commercial anti-fogging prod¬ 
ucts already on the market was also investigated. 

Wetting Agents 

Twenty-one wetting agents (see Table 5) were 
tested to determine their effectiveness by applying 
each to a glass surface which was then cooled below 
the dewpoint of air, dried, cooled again, and so on. 
The number of such fogging cycles through which 
a single application of a wetting agent would main¬ 
tain visibility was taken as a measure of its effective¬ 
ness. 

Most of these wetting agents were found to be ef¬ 
fective on only the hrst fogging cycle, but six of 
them—Aerosol 18, Aerosol OT 100%, Alkanol B, 
Alkanol WXN, DuPont 189 S, and Igepon T Gel— 
gave distinctly better results. In order to develop a 
compound which could be applied quickly, easily, 
and effectively by relatively unskilled personnel. 


a moistened cloth. The film of wetting agent re¬ 
maining on the glass is buffed lightly with a clean 
soft cloth until the surface is clean. 

Field tests of Type 1-A were conducted by the U. S. 
Navy Carrier Command at Pearl Harbor, with the 
material applied to the lens elements of telescopic 
sights, portions of the windshields, and instrument 
dial glasses of two planes which then were dived 
from an altitude of 20,000 feet and leveled off at 
1,000 feet above sea level. The results were compared 
with untreated surfaces exposed to the same condi¬ 
tions. 

To meet a demand for an anti-fogging compound 
in paste form, Aerosol OT 100% was combined with 
bentonite, precipitated calcium carbonate, alcohol, 
and water to give Anti-fog Compound, Experimental 
Type 1— C. In addition, Aerosol OT 100% was com¬ 
bined with “Carbowax 4000” and glycerine to give 
an anti-fogging compound in the form of a solid 
stick. 

Commercial Anti-Fogging Compounds 


Table 5. Wetting Agents. 


Tradename Manufacturer 


Aerosol OS 
Aerosol 18 
Aerosol OT 100% 
Aerosol OT—Calcium 
salt of 

Aerosol OT—Zinc salt 
of 

Alkanol 11 
Alkanol WXN 
Amine 220 
Defoamer 33 
Duponol ME 
Dupont Ml* 189S 
Igepal CTA 
Igepon AP Extra 
Igepon T Gel 
Tergitol Penetrant 4 
Tergitol Penetrant 7 
Tergitol Penetrant 7 
plus triethanolamine 
Tergitol Penetrant 
ME A 

Wetting Agent 521 
Wetting Agent 35-11 
Wetting Agent 58-11 


American Cyanamid & Chemical Corp. 
American Cyanamid & Chemical Corp. 
American Cyanamid & Chemical Corp. 
American Cyanamid & Chemical Corp. 

American Cyanamid & Chemical Corp. 

E. I. DuPont deNemours and Company 
E. I. DuPont deNemours and Company 
Carbide and Carbon Corporation 
Carbide and Carbon Corporation 
E. I. DuPont deNemours and Company 
E. I. DuPont deNemours and Company 
General Dyestuff Corporation 
General Dyestuff Corporation 
General Dyestuff Corporation 
Carbide and Carbon Corporation 
Carbide and Carbon Corporation 
Carbide and Carbon Corporation 


Carbide and Carbon Corporation 
Commercial Solvents Corporation 
Victor Chemical Works 
Victor Chemical Works 


solutions of these agents in volatile solvents were 
then prepared and tested. The most promising ap¬ 
peared to be a 3 per cent solution of Aerosol OT 
100% in carbon tetrachloride, which is listed as Anti- 
Fog Compound, Experimental Type 1-A, and which 
can be applied either by spraying or by rubbing with 


Thirteen compounds on the market as anti-fogging 
preparations were also investigated (see Table 6). Of 
these, some are effective over only a short period, a 
few possess more lasting activity, while the two best 
appeared to be Antimist and Cellosize WS Solution. 
These two were tested for their resistance to repeated 
fogging cycles. 

Lacquer Wetting Agent Coating 

Since it had been found early in this investigation 
that the durability of even the best wetting agent 
compositions is quite limited and that frequent re¬ 
application is necessary, attempts were made to find 
some method of prolonging their effectiveness. This 
problem resulted essentially in seeking a method 
that would keep the wetting agent on the surface. It 
was reasoned that, if the wetting agent could be in¬ 
corporated in a lacquer-type coating, a higher con¬ 
centration of wetting agent could be deposited on the 
surface and, at the same time, the rate of solution of 
the wetting agent would be retarded. 

Since it is more compatible with organic solvents 
than are the other wetting agents available, Aerosol 
OT 100% was tested in combination with a number 

w A fourth possible method—heating the vision surfaces so 
that their surface temperature is always higher than the dew¬ 
point temperature of the surrounding atmosphere—was not in¬ 
vestigated since it was already being studied by other workers. 


Ft F"> F NTEA 4. 










310 


SPECIAL DEVICES 


of resins and lacquers. Preliminary experiments 
showed that the most satisfactory combination was 
one incorporating Aerosol witli a waterspar lacquer 
(cellulose nitrate base), ethyl acetate, and butyl 
acetate. Coatings made from this material were then 
tested for ability to withstand repeated fogging 
cycles and for their solubility when completely im¬ 
mersed in water. 

Water-Absorbent Films 

The possibility of preparing coatings which would 
prevent fogging of vision surfaces by absorbing any 
condensed moisture was studied in an effort to de¬ 
velop a film which would possess not only good opti¬ 
cal quality and resistance to injury by normal wear, 
but also the property of regeneration, that is, the 
ability to absorb moisture when condensation occurs 
and to dispel it when the film is returned to condi¬ 
tions of normal humidity and temperature. After a 
search of the literature and a number of preliminary 
experiments, it was decided that the most promising 
material is a gelatin film containing glycerin-water 
solutions as dispersion media. Films in which the 
dispersion medium is dilute with respect to glycerin 
lose water to the atmosphere until an equilibrium is 
reached at the point where the partial pressure of the 
water in the atmosphere reaches the value of the 
partial pressure of water in the glycerin-water solu¬ 
tion. 

Experimental gelatin-glycerin-water films were 
therefore prepared and tested for resistance to re¬ 
peated fogging cycles and normal handling. Attempts 
were also made to produce hard and highly resistant 
films by treating the gels with formaldehyde and with 
potassium dichromate. 

Special attention was given to a moisture-absorbing 
film developed by William C. Geer, Ithaca, New 
York. 

Desiccating Devices 

With some optical instruments, internal fogging 
may be prevented by drying the air surrounding the 
inner surfaces and then sealing the instruments 
completely. Often, however, the construction of the 
instruments makes it extremely difficult to create a 
permanent airtight seal, and in some cases such a seal 
used on aircraft with changing atmospheric pressure 
may strain and damage the instrument. 

An alternate method was consequently developed 
for the Mark 111—7 telescopic sight provided by the 


U. S. Navy Bureau of Ordnance. This sight was first 
completely overhauled and reassembled, all external 
glass-metal and metal-metal joints were sealed with 
rubber cement, and only the objective vent hole was 
left open. To this hole was fitted a drying tube filled 


Table 6. Commercial Anti-Fogging Compounds. 


Trade name 

Manufactu rer 

A. F. C. 44 

Continental 1 laboratories 

Anticloud 

American European Chemical Co. 

Anti-fog lens stick 

American Optical Co. 

Antimist 

Welmaid Manufacturing Corporation 

Cellosize WS solution 
for anti-fogging films 

Carbide and Carbon Chemicals Corp. 

Fogpruf (paste and 
liquid) 

Mine Safety Appliances Co. 

K leer-Vue 

Scientific Cleansing Products Corp. 

Mystic 

American Products Company 

No-Fog cloth 

Soilicide Laboratories 

No-Mist 

Scientific Cleansing Products Corp. 

Samae No-Mist 

Samae Products Co. 

Triteen 

Trident Manufacturing Company 

Triteen ^2 

Trident Manufacturing Company 


with silica gel x and equipped at the outer end with 
a two-way valve designed to open in either direction 
under a small pressure differential. After final as¬ 
sembly, the sight was tested by being subjected to a 
temperature of 20 C for 20 minutes and then placed 
suddenly in an atmosphere at a temperature of 26 C 
and a relative humidity of 70 per cent. 

18,7-2 Results 

Wetting Agents 

In the tests on Anti-Fogging Compound, Experi¬ 
mental Type 1-A, no fogging occurred on the treated 
surfaces when the planes were dived from an altitude 
of 20,000 feet to 1,000 feet above sea level. In compari¬ 
son, similar untreated surfaces were found to fog 
when the planes were dived to approximately 7,000 
feet. The coating on the sights retained their effi¬ 
ciency while the planes were flown twice a day for a 
week. I he coated windshields were occasionally 
rubbed with a clean dry cloth to remove clust, but 
otherwise were in good condition at the end of the 
week. Anti-Fogging Compound, Experimental Type 
1 —C, prepared as a paste, gave similar results. 30 

Commercial Anti-Fogging Compounds 

Of the commercial compounds tested, Cellosize WS 
Solution was found to be as effective as the new ex¬ 
perimental types developed. 

x No. 22110 Silica Gel Dryer, manufactured by the Weather- 
head Company, Cleveland, Ohio. 









SINE-DISK PROPELLERS 


311 


Lacquer Wetting Agent Coatings 

Coatings made from Aerosol OT 100%, waterspar 
lacquer, ethyl acetate, and butyl acetate maintained 
good visibility over 14 fogging cycles. Soaking the 
films in water for more than 1 hour failed to strip 
them from glass. In contrast, other lacquer coatings 
tested were stripped completely from glass after 
soaking for only a few minutes. 

These coatings unfortunately possess definite dis¬ 
advantages. They are soft as compared with glass, 
and tend to pick up dust and dirt which cannot be 
removed without injuring the films. The coatings 
may be removed and renewed when they have lost 
their effectiveness, but this is a rather troublesome 
procedure. The optical quality of the films is only 
fair, but might be improved by further studies of ap¬ 
plication methods. In spite of the advantages pos¬ 
sessed by the best of these films, their disadvantages 
were found to be sufficiently serious to warrant termi¬ 
nation of this phase of the research. 

Water-Absorbent Films 

In fogging cycle tests, the gelatin-glycerin-water 
films withstood a considerable number of cycles, 
but they were found not hard enough to withstand 
normal handling without injury to the surfaces, and 
their optical quality left much to be desired. Attempts 
to harden these films by chemical treatment were not 
successful. For these reasons further work on this ap¬ 
proach to the problem was discontinued. 

The Geer moisture-absorbing film was found to be 
capable of preventing fog, but it, too, is not hard 
enough for practical application. 

Air Desiccation Devices 

The silica gel drying tube applied to the Mark 
111—7 telescopic sight was found to keep the optical 
surfaces perfectly clear when the sight was chilled 
and then plunged into warm, moist air. Similar sights 
not equipped with the drying tube were completely 
fogged under this treatment. 

1873 Conclusions 

The methods, materials, and devices developed in 
this research require further field testing and develop¬ 
ment. In particular, the use of desiccating tubes 
such as the one applied to the Mark 111—7 telescopic 
sight warrants additional study. Drier assemblies 
are generally applicable to other optical instruments, 



Figure 20. Sine-disk propeller installed on Navy plane 
personnel boat. 


double windshields, and similar vision devices which 
are subjected to large pressure changes, and seem to 
offer the most satisfactory and positive method to pre¬ 
vent fogging of such devices. The style, size, and loca¬ 
tion of the drier would have to be studied for each 
particular instrument. The drying tubes may be made 
of transparent plastic and filled with drying agents 
impregnated with indicator dyes which indicate by a 
color when the drying agent requires renewal. 

i 8 8 SINE-DISK PROPELLERS' 

Summary 

A sine-disk propeller was investigated during the 
spring and summer of 1944 for use on a shallow 
draft boat. Under the conditions of the tests, the de¬ 
vice gave a maximum speed of only about 15 mph, 
marked by considerable cavitation and vibration. It 
was expected that better hull design and engine-to- 
propeller gear ratios would give improved perform¬ 
ance. 

The design of the new propeller permits operation 
in shallow water considerably fouled with marine 
growths. 

18 81 The Problem 

A sine-disk propeller, consisting of an opposed 
pair of partially immersed wobble- or sine-disk ele¬ 
ments, mounted on a transverse shaft immediately 


y Project NS-160. 

















312 


SPECIAL DEVICES 



Figuri 21. Navy plane personnel boat equipped with 
sine-disk propeller under way at about 13 mph. 


abaft a transom, had been proposed by its inventor* 
for use in shallow draft operations. In 1943 an 
investigation was initiated to determine the me¬ 
chanical feasibility, practicability, and relative effi¬ 
ciency of the device. 1111 

1882 Procedure 

The sine-disk propeller( Figure 20) was installed on 
a U. S. Navy Mark II Plane Personnel Boat powered 
with a 6-cylinder, 115 blip engine. With screw pro¬ 
pulsion, its top speed ranges from 24 to 30 mph. 
In order to accommodate the new propeller, the 
engine was placed in the stern abaft a plywood bulk¬ 
head, and the fuel tank was moved just abaft the 
forward cockpit. The after deck was extended for¬ 
ward to the bulkhead, and a suitable hatchway and 
covers were fitted on. 

The propeller itself was designed with three pos¬ 
sible longitudinal positions for the transverse shaft: 
a vertical or height adjustment through a consider¬ 
able range; two breadth dimensions; a series of three 
gear sets which, with an interposed engine gearbox, 
provided six engine-to-propeller ratios; and a wide 
range of both flat and warped disks of varying angles, 
diameters, and peripheral shapes. To determine the 
effect of increased segment dimensions at small di¬ 
ameters, a series of midtipie-segment rotors was pro¬ 
vided in four angle and axial length combinations. 
Several built-up plywood shrouds and housings were 
constructed for a study of the effect of baffling anil 
shrouding. 

With this equipment, trials were run on the Sagi- 


z C. D. Van Patten, Detroit, Michigan. 

in* This investigation was conducted by the F. L. Jacobs Com¬ 
pany, Detroit, Michigan, under OSRD contract OEMsr-1188, 
and Sparkman & Stephens, Inc., New York, New York, under 
OSRD contract OF.Msr-154. 


naw River and in Saginaw Bay during the spring 
and summer of 1944, and observations were made on 
a large number of trial assembly combinations (Fig¬ 
ure 21). Special runs were made in weed-choked 
waters, over shoals and obstructions, through flotsam, 
anil on beaches. As an added experiment, towing 
tests were made with the boat accelerated by means 
of a towline to a speed above the stern eddy range, 
when the line was cast off anil the test boat proceeded 
under its own power. 

188:5 Results 

The maximum speed achieved from a standing 
start in these tests was about 13 mph. Cavitation 
appeared to be one of the most critical factors, per¬ 
haps the limiting one, and, particularly in the earlier 
trials, vibration was intense. 

When the boat was towed to a speed above the 
stern eddy range anil then released, it cotdd main¬ 
tain a speed of 20 to 24.7 mph. 

Tests of the three basic forms of disk investigated— 
flat, warped, and removed-segment or ellipsoid—in¬ 
dicated that the warped and the ellipsoid shapes 
give the best results, with the warped type giving 
slightly smoother operation. 

While it was found possible to batter and dent 
the disks on hard ground, it was virtually impossible 
to destroy their propulsive power. In all of the marine 
growths in which the boat was tried, the sine-disk 
propeller appeared to be entirely immune to fouling. 

File boat steered satisfactorily at all but the very 
lowest speeds. 

18-84 Conclusions 

The maximum speed achieved—about 43 per cent 
of that expected—appeared to be limited by cavita¬ 
tion, unsuitable engine-to-propeller ratios, uncon¬ 
trolled depth of immersion, and a hull design un¬ 
satisfactory for this type of propeller. 

Further development may well be undertaken on 
application of the sine-disk propeller to the planing 
type of hull to be used in comparatively high-speed 
aircraft rescue boats, and to the nonplaning type, 
where the advantages of shallow draft, nonfouling, 
and structural durability can be useful. 32 

Independent observations led to the conclusion 
that in the tests undertaken, either the disks were 
too small to propel the boat properly or the gear 
ratio was too high for the engine to turn disks large 

















COLD WEATHER STARTING 


313 


enough to give the necessary propulsive thrust. No 
simple, practical method was achieved to permit 
critical analysis of the performance of the sine-disk 
propeller. 33 

COLD-WEATHER STARTING' ,b 

In ihe summer of 1942, the Ordnance Department 
requested an investigation which would facilitate 
starting tank engines after they had been exposed to 
temperatures as low as -40 F. Assistance was re¬ 
quested specifically on the development of (1) a 
shutter arrangement operated from inside the tank 
for heating the engine and the oil lines during start¬ 
ing periods, (2) a primer pump for oil dilution, (3) 
space heaters for maintaining minimum tempera¬ 
tures of 5 to 10 F during nonoperating periods and 
for heating the battery, oil line, and engine during 
starting operations, (4) an immersion heater to be 

bb Project OD-62. 


operated from the storage battery to heat the oil in 
the reservoir, and (5) a conversion kit for installation 
of the above equipment on tanks in service. 

While this investigation was under way, the Army 
itself developed shutters which appeared satisfactory, 
and several primer pumps and space heater designs 
were made available for consideration. 

Major emphasis was placed on the immersion 
heater, with a design finally being developed for a 
coil to heat the oil at the sides and bottom of the 
reservoir and around the reservoir outlet at the base 
of the hopper. 00 In laboratory tests with oil having 
a pour point of 0 F, this unit required 10 minutes to 
warm the oil from -16 F to a fluid state. 

With these developments and the equipment in¬ 
stalled on tanks for the winter months, the Ordnance 
Department advised that the work under the original 
directive had been successfully completed, and the 
project was terminated. 

ce Calrod Heater, manufactured by General Electric Co., 
Schenectady, N. Y. 







Chapter 19 

SPECIAL STUDIES 


*9 i SHIP TURNING RESEARCH 
Summary 

I n order to investigate the principal hull factors 
affecting the turning of ships, particularly destroy¬ 
ers, a turning basin was constructed and measure¬ 
ments conducted on a series of models representing 
several variations of round- and V-bottom destroyer 
hulls and on a series of hulls covering the transition 
from destroyer to PT boat proportions. Additional 
studies were made on actual Navy ships. 

In general, it was found that short turning is fa¬ 
vored by a deep profile forward and a shallow profile 
aft, smooth afterbody sections, increased displace¬ 
ment, twin rudders, and the presence of bilge keels. 

At the termination of the project under NDRC 
direction, work was continued under Navy super¬ 
vision. 

1911 The Problem 

At the request of the Navy, work was undertaken 
early in 1942 to determine the principal hull factors 
affecting the turning of ships. The eventual goal was 
the improvement of such ships as destroyers, which 
were believed to suffer particularly front deficient 
turning characteristics. It was determined that the in¬ 
vestigation should begin with tests of systematic hull 
variations in order to establish trends and provide 
general background and should later include a study 
of steering. 

in maneuvering against an enemy, a warship must 
frequently turn sharply through 90 or even 180 de¬ 
grees. It is of the highest importance that this maneu¬ 
ver be carried out (f) with a minimum turning circle, 
(2) with minimum loss in speed, and (3) without un¬ 
due heel. The behavior of a ship in making such 
turns appears to depend upon (1) the form of the 
underwater body, (2) the rudder area, (3) the rudder 
angle, (4) the position of the rudder or rudders in re¬ 
lation to that of the propeller or propellers, and (5) 
the speed of the ship. 

Before 1939, this type of investigation consisted 
largely, in this country, of model turning tests con¬ 
ducted in the Experimental Model Basin at the Wash¬ 
ington Navy Yard. These were limited to partial 


turns. In 1939, turning tests were made in the Stevens 
Institute swimming pool in order to observe the heel 
of a destroyer model during turning. In 1941, turning 
tests of three competitive motorboat designs were 
made in the somewhat larger swimming pool at Co¬ 
lumbia University. In 1941 and 1942, a comparative 
study was made by the Navy of the turning of two 
destroyer models and three cruiser models in an effort 
to discover why destroyer turning circles are rela¬ 
tively larger than cruiser turning circles. These early 
tests showed that (1) turning tests of small models are 
generally satisfactory and (2) a tank somewhat larger 
and more conveniently arranged than a swimming 
pool is necessary to handle any considerable volume 
of work. 

1912 Procedure 

In order to conduct the investigation requested by 
the Bureau of Ships, a it was necessary to construct a 
suitable turning basin and to equip it with the facili¬ 
ties necessary for investigating the turning character¬ 
istics of high-speed ships. This was desired in order to 
permit an analysis of cruiser turning; equal attention 
was, however, focused on destroyers, which then were 
performing antisubmarine duty and which required 
improved maneuvering. The maneuvering tank built 
for this purpose is 75 feet square and 4i/9 feet deep, 
with a 25-foot extension at one corner to provide ad¬ 
ditional length for straight-approach runs. 

In this tank, the comparative turning tests were 
conducted on 18 hull variations of a round-bottom 
destroyer, on 13 hull variations of a V-bottom de¬ 
stroyer selected because of its good turning, and on a 
group of V-bottom hulls which covered the transition 
from destroyer to PT boat proportions. Other tests 
were conducted on the effect on turning of various 
appendages, such as bilge keels; and of changes in 
the number, size, and relative angular displacement 
of rudders, in propeller size, and in relative propeller 
speeds. Statistical and analytical studies were carried 
out on tactical data derived from trials made for the 
Navy on 22 models and 13 ships. The lateral rudder 


a This investigation was conducted by the Stevens Institute of 
Technology, Hoboken, N. J., under OSRD contract OEMsr-458. 



314 


C 





SHIP TURNING RESEARCH 


315 


force of a few representative models, both in turning 
and in straigln-line motion, with yaw, was measured 
and analyzed. 

In general, the tests were divided into two basic 
types: 

1. The measurement of the approach and turning 
path at various conditions of speed and rudder angle. 

2. The measurement of the lateral rudder force in 
free turning at various rudder angles and of the lat¬ 
eral hull force and hull moment in straight-line mo¬ 
tion at various yaw angles. 

The first group concerns the geometry of turning, 
the second, the forces operative in steering and 
turning. 

In addition to the turning tests, resistance tests 
were also run on many of the models investigated, 
particularly on the variations of a round-bottom de¬ 
stroyer, in order to show the influence upon resist¬ 
ance of the hull variation under investigation. 

Various other projects, nearly all of them bearing 
directly on the turning problem, included compara¬ 
tive model tests made in cooperation with the Taylor 
Model Basin, shallow water tests to investigate the 
possible effect of shoal water upon the results of 
tactical trials, resistance tests of heavy-displacement 
models, conducted at the request of the War Depart¬ 
ment, and the design and construction of a three- 
component rudder dynamometer for use at the 
Taylor Model Basin in measuring the lift, drag, and 
torque on the rudder of large models. 

Some of the foregoing work was interrupted at the 
request of the Navy for high priority measurements 
and study of tactical data for models of some 22 naval 
vessels, to be used by the forces afloat, and for the 
execution and analysis of full-scale tactical trials of 
13 naval vessels. All of this work was covered by sepa¬ 
rate contracts with the Navy. 

19,1,3 Results 

From the information obtained before this con¬ 
tract was terminated and the project transferred to 
the Navy, it is possible to draw certain over-all con¬ 
clusions on the relationship of hull proportions and 
turning: 

1. Profile. A deep profile forward and a shallow 
profile aft combine to favor short turning. The stern 
of a ship has a pronounced lateral motion during 
turning, and a high profile aft minimizes the resist¬ 
ance to this motion. This is substantiated by tests at 


abnormal trims: static trim by the bow improves 
turning, while static trim by the stern impairs it. 

2. The afterbody shape. Smooth afterbody sec¬ 
tions—that is, the absence of sharp chines or angular 
sections—and the reduction of dead wood or removal 
of a skeg improve turning. 

3. An increase in displacement, displacement- 
length ratio, or beam-draft ratio slightly improves 
turning. 

4. Although the propellers of a turning ship do not 
both rotate at the same rate, even with the throttle 
remaining undisturbed, it is satisfactory to conduct 
model tests with all propellers rotating at the same 
speed. 

5. Smaller turning circles with the same average 
rudder angle can be obtained with ships having twin 
rudders if the rudder nearer the center of the turn is 
turned more than the average and the other rudder 
is turned less than the average. 

6. Twin rudders are much more effective than a 
single rudder. 

7. The presence of bilge keels results in a reduc¬ 
tion in the size of the turning circle but in an increase 
in outward heel during turning. 

A correlation of a large amount of tactical data has 
shown that, when turning in circles of similar size 
(measured in terms of ship length), all ships have 
much the same relative turning geometry—i.e., ad¬ 
vance, transfer, and speed reduction. This indication 
has simplified the approach to further studies. 

191,4 Recommendations 

The ultimate aim in these investigations was the 
development of operational data covering a suffi¬ 
ciently wide variety of forms of underwater body, 
rudder area and angle, and similar factors that the 
results could be expressed as functions of two or three 
parameters involving all of the factors influencing 
the performance of a ship in turning. These para¬ 
meters should be expressed in such a manner that, 
given a proposed ship operating under proposed con¬ 
ditions, the diameter of the turning circle and the loss 
of speed can be read from a suitable form of chart. 

This end lies yet in the future, but the information 
accpiired marks considerable progress toward the 
goal. 

At the termination of this project under NDRC, 
work was already under way toward four major ob¬ 
jectives. The measurement of forces and turning 






316 


SPECIAL STUDIES 


characteristics should be continued on four more of 
the group of models representing a typical spread of 
hulls. The data obtained in this study should be cor¬ 
related with the equations of motion to ascertain the 
influence of the several hull variables represented. 
On the basis of the information obtained from the 
two foregoing studies, tests should be conducted on a 
short, consistent, exploratory series of hulls and car¬ 
ried out to show the type of range of hull variables 
which must be investigated to provide general design 
information. Then, as a logical step, tests should be 
conducted on a more complete series of hulls to pro¬ 
vide fundamental data for use in design. It appeared 
that future investigations should be directed toward 
obtaining suitable empirical data so that a basic 
theory (equations of motion) can be transformed into 
workable design information on turning and steer¬ 
ing. Achievement of this goal would mark a consider¬ 
able improvement over the available “cut-and-try” 
method based on rule of thumb data. 

19-2 CAVITATION RESEARCH 1 

At the request of the Taylor Model Basin of the 
U. S. Navy Bureau of Ships, work was begun in the 
summer of 1944 on a study of the cavitation produced 
by various shapes of noses and tail pieces. 0 Before this 
project was terminated, a water tunnel was con¬ 
structed, together with several interchangeable noses 
and a supporting cylindrical shaft. Each nose con¬ 
tained necessary leads for piezometric measurements. 
Provisions were also being made for high-speed pho¬ 
tographic recording of the onset, physical forms, and 
characteristics of cavitation as the speed is gradually 
increased from low to cavitating velocity. 24 

19.3 the PHYSICAL CHARACTERISTICS 
OF SNOW AND THE PERFORMANCE 
OF SNOW VEHICLES 

Summary 

In an attempt to correlate the performance of dif¬ 
ferent vehicles, including the Weasel, on snow char¬ 
acterized by different properties, it was found that 
vehicle performance is affected by the density and 
depth of the snow, the penetration into the snow at 

1> Project NS-294. 

c This investigation was conducted by the Hydraulic Re¬ 
search Institute of the State University of Iowa, Iowa City, Iowa, 
under OSRD contract Symbol 1127. first under the supervision 


different ground pressures, the water content of the 
snow, and, particularly, the shearing strength of 
the snow at different ground pressures. In general, 
the shearing strength is the principal controlling fac¬ 
tor and is apparently the limiting factor on maxi¬ 
mum climb. The water content of the snow parallels 
the icing condition on moving metal parts, and a 
high water content in certain types of snow drasti¬ 
cally lowers the shearing strength. Depth and pene¬ 
tration affect operation on the level and on hills. The 
density of the snow does not appear to have a direct 
bearing on vehicle performance but is involved in 
determining the proportions of air, water, and ice. 
The depth as such does not seem to affect the rolling 
resistance of the vehicle but is important in its effect 
on the penetration necessary to compress the snow 
sufficiently to support the vehicle. 

Correlation of these factors with meteorological 
conditions has shown that it is possible to make satis¬ 
factory forecasts of vehicle performance not merely 
for a period of 12 to 24 hours but, under certain cir¬ 
cumstances, for several days ahead. 

19-3,1 The Problem 

As part of the development of the Weasel/ 1 it ap¬ 
peared highly desirable to conduct a parallel inv esti¬ 
gation on the terrain over which this snow vehicle 
was expected to operate. It was apparent at die outset 
that not only were the major physical characteristics 
of snow in their relationship to vehicle performance 
poorly understood, but even the identity of some of 
these characteristics was unknown. It was likewise 
evident that the properties of snow may vary over an 
extremely wide range and may change from one ex¬ 
treme to another in a very short time. 

Since the Weasel was being prepared as both a 
logistical and a tactical vehicle for use in what was to 
be a carefully planned winter invasion, it was essen¬ 
tial that an additional investigation be conducted on 
both short- and long-range forecasting of snow condi¬ 
tions. Successful methods derived from this phase of 
the study would make it possible to indicate the prob¬ 
able speed, hill-climbing ability, and maneuverabil¬ 
ity of the Weasel over a known terrain well in ad¬ 
vance of the actual operation. 

ot Section 12.1. later under Division 6, and finally under the 
Navy. 

(1 See Chapter 5 in this volume. 


LL)^!nihN'R-VT 






PHYSICAL CHARACTERISTICS OF SNOW 


19,3,2 Procedure 

Active work on this problem 0 began in August 
1942 at the Columbia Ice Fields, Saskatchewan, Can¬ 
ada, during the tests of the first Weasel pilot models 
on the Saskatchewan Glacier. Additional work was 
carried out in the Columbia Ice Fields in October 
1942, while other studies were made at Camp Hale, 
Colorado, from February to May 1943 and at Pink- 
ham Notch, New Hampshire, in February 1943. 

Nomenclature 

Snow as it appears on the ground may be classified 
as freshly fallen snow, settled snow, crusted snow, and 
firn snow, and each of these broad groups may be sub¬ 
divided into several subgroups determined by condi¬ 
tions of radiation, wind, and temperature during 
their life history. From the point of view of vehicle 
performance, these various types of snow may be clas¬ 
sified as follows: 28 

A. Freshly Fallen Snow 

1. Wet flakey snoxc — temperature 32 to 40 F; wet, 
highly compressible, and coherent; density varying 
from 0.1 to 0.4; water content up to 25 per cent. 

2. Dry flakey snow— temperature 24 to 32 F; com¬ 
pressible and coherent; density about 0.2. 

3. Powder snow, dry— temperature varying greatly 
from about 30 F to about 10 F; compressible but 
poorly coherent; density below 0.2. 

4. Tough powder or flour snow— temperature + 10 
to —20 F; compressible but incoherent; density in 
the vicinity of 0.2. 

5. Wild snow— temperature below about 20 F; very 
fluffy, like “diamond dust”; density below 0.05. 

B. Settled Snow 

(i. Sun-toughened snow— usually 2 or more days 
old; density 0.2 to 0.3; compressible and coherent. 

7. Wind-toughened snoxc— no appreciable crusts 
but firm; density 0.2 to 0.3; compressible but poorly 
coherent. 

8. Snoxc cushion— snow that has been deposited by 
wind, occurring at low temperatures and resembling 
tough powder snow (see above), except that its dens¬ 
ity is greater. 

e This investigation was conducted by personnel of the Brook¬ 
lyn Polytechnic Institute, Brooklyn, New York, under OSRD 
contract OF.Msr-878, and a representative of the Norwegian 
Army, in cooperation with personnel supplied by the Stude- 
baker Corporation, South Bend, Indiana. 


9. Wind slab— resembles snow cushion but is hard¬ 
er and more unstable, since it does not adhere to the 
snow surface beneath. (Note: Wind slabs and snow 
cushions, like cornices, are local phenomena and are 
of interest only as formations that should be avoided.) 

10. Sand snoxc— occurs at extremely low tempera¬ 
tures; incoherent and incompressible; tough like 
sand, with no glide; density about 0.4 to 0.5. 

C. Crusted Snoxc 

Light crusts may be present on top of loose snow, 
but strong crusts are usually supported by dense 
snow. Carrying strength depends mainly on thick¬ 
ness, but the relationship was not determined. 

11. Wmd crust— formed through the drifting of 
coherent snow, usually rough surface with skavler 
and erosion marks; density 0.3 to 0.5. 

12. Su?i crust— formed through repeated melting 
and freezing of the snow surface exposed to sunshine; 
usually smooth; density 0.3 to 0.5. 

13. Rain crust— formed through freezing of the 
snow cover after rain, usually hard like ice. 

1). Firn Snoxc 

Through repeated melting and freezing, the snow 
develops a granular structure, with a frozen crust 
during cold spells (night) and a soggy, granular 
composition in warm periods (day). Three types are 
noted: 

14. Spring snow— slightly granular; density 0.3 to 
0.4; wet, with water content about 5 per cent in the 
middle of the day; compressible and coherent. 

15. Corn snoxc or moderate firn snow— large 'whit¬ 
ish grains with a tendency to ice; water content 5 to 
15 per cent in the middle of the day; density about 
0.5; poorly coherent, not very compressible. 

16. Coarse firn snow— large opaque grains, some¬ 
times ice; very wet and soggy, water content about 
20 per cent during warm spells; density 0.5 to 0.6; 
compression and cohesion extremely limited. 

Surface hoar and thin rime crusts may form on the 
surface of any of the above types but do not affect 
vehicle performance. 

The nomenclature in the foregoing outline will 
be used in the rest of this report. 

Observations 

In planning the actual measurements to be made, 
particularly those to be taken on the Saskatchewan 
Glacier, it was felt that two main principles should 









318 


SPECIAL STUDIES 


be used as guides: (1) the tests should be so quick and 
simple that they could be carried out on the proving 
ground right next to the operating vehicle, and (2) 
the experimental setups should not differ signifi¬ 
cantly from those used in earlier snow research, so 
that the results could be compared.- 5 

Density. The weight of a known volume—about 
2 liters—of snow was determined with a spring bal¬ 
ance. When made at virtually the same time at the 
same location, the measurements varied about 1 to 
2 per cent. Under the conditions on the Saskatchewan 
Glacier, the observed densities were between 0.54 
and 0.60, marking a typical heavy snow. In spite of 
the fact that the density remained practically con¬ 
stant and therefore was an inappropriate factor for 
consideration as a parameter, density measurements 
were made throughout the entire period of observa¬ 
tion. In other areas, particularly at Camp Hale, 
values as low as 0.07 were found. 

Temperature. The temperature of the snow was 
measured 1 to 2 inches below the surface and re¬ 
mained very close to 32.00 ±0.05 F in that region. At 
depths of 2 to 5 feet, however, the snow temperature 
dropped gradually from 31 to 30 F. Air temperature 
measured from 6 to 8 inches above the snow surface 
varied according to weather conditions from 21 F 
on a cool morning to 47 F on a warm afternoon. Air 
temperature showed a marked relationship to the 
mechanical and physical properties of the snow, with 
rising temperatures always accompanied by higher 
water content, increased penetration, and decreased 
shearing strength. Quick and temporary variations 
in air temperature, caused by sudden breezes or drift¬ 
ing clouds, had no measurable inlluence on snow 
properties. 

Water Content. The heat of melting of a known 
weight of snow was determined calorimetrically and 
gave the water content, which, varying from 2.5 to 
more than 25 per cent during a warm day, was found 
to be intimately connected with shearing strength 
and penetration. The greater the water content, the 
softer and weaker was the snow. Microscopic obser¬ 
vation indicated that this is due to the fact that each 
spongy snow grain becomes enveloped in a thin film 
of water which not only interrupts the interlocking 
of the particles but actually has a definite lubricating 
effect. In such a condition the grains “swim” in water. 
A similarly striking correlation was found between 
high water content and icing of the metal parts of 
the vehicles. Icing became apparent when the water 


content reached 15 per cent and was always very 
severe at 25 per cent. 

Shearing Strength. Shearing strength tests were 
conducted by shearing oil a snow column supported 
by two metal tubes. The results are expressed in psi. 
The accuracy of this test should not be overestimated, 
since the strength of the snow columns in the tubes 
depends considerably upon the method used to bring 
the snow into the tubes. If the same procedure is fol¬ 
lowed in every case, the measurements can be repro¬ 
duced within ±30 per cent. 

Shearing strength usually showed a very marked 
change during the day. After a cool night it was 
often too high to be measured. At about 1000 hours, 
after the sun had worked on the snow for 2 or 3 
hours, values of 1.5 to 1.8 psi were obtained. Toward 
1200 hours the shearing strength dropped very 
quickly and in the early afternoon at about 1400 
hours reached values of 0.30 psi and less. If clouds ap¬ 
peared during the day, the drop in shearing strength 
stopped abruptly and values of about 0.6 psi were ob¬ 
served all during the afternoon. At about 1630 or 
1700 hours, as the air temperature started to go 
down, the shearing strength increased. 

If the night were warm—about 36 F—with shearing 
strength values of about 0.6 or 0.8 psi, these values 
dropped during the day as soon as the sun touched 
the snow surface. On a cloudy day with little or no 
direct sunlight, however, the shearing strength re¬ 
mained constant throughout the day. 

Penetration. In this test, which was carried out 
mainly because earlier workers had reported a series 
of such measurements, the depth and penetration 
were measured for a weight falling from a height of 
10 inches above the snow. The values cannot be con¬ 
verted directly into any rational quantity, such as 
compressibility, shearing strength, or the like. The 
penetration can be measured in a few seconds and 
the individual tests checked to about 25 or 35 per 
cent of their own value. In the morning after a cool 
night, penetration was usually found to be about 
0.25 inch or less, characteristic of the hard, old snow 
on the Saskatchewan Glacier. Later during the day, 
penetration increased to about 2.5 inches and always 
varied inversely as the shearing strength. Since this 
test can be made without removing a sample, it of¬ 
fered an opportunity to study the local conditions of 
a snow surface of specific interest in connection with 
a vehicle test; thus, it was possible to measure the 
penetration value in the track of the Weasel after 






PHYSICAL CHARACTERISTICS OF SNOW 


319 


the vehicle had passed and to see which parts of the 
track were compressed and reinforced and which 
were loosened and weakened. It was also possible to 
compare the penetration into the snow on the snnsiclc 
and on the shadow side of the small snow hills which 
covered nearly all the glacier proving ground. These 
measurements revealed the occurrence of great local 
variations, with a penetration value of 2.0 inches 
observed on the sunside and a value of only 0.30 inch 
at a point perhaps 5 or 6 inches away on the shadow 
side. It was evident, therefore, that small crusts or 
disks of relatively hard snow are frequently distrib¬ 
uted in a soft matrix, but as long as these hard por¬ 
tions are not coherent, they contribute little to the 
apparent average shearing strength of the snow. 

Other Tests. It must be pointed out that there is 
no reason to believe that the tests described above 
provide the best or simplest means of characterizing 
a given snow condition. Most probably they provide 
only a very crude solution of the problem of nu¬ 
merically representing snow properties. Selected 
from the point of view of expedience and simplicity, 
they showed some definite weaknesses and disad¬ 
vantages. 

Several additional tests were contemplated but 
either applied only irregularly or not used at all. 



Figure 1. Relationship between snow penetration and 
ground pressure, Saskatchewan Glacier, August and Oc¬ 
tober 1942. 


For example, it was planned to measure the shearing 
strength of a snow sample after a previous compres¬ 
sion—a test which would lead to a curve of shearing 
strength versus ground pressure. The snow on the 
glacier, however, did not lend itself readily to this 
test, and accordingly such curves were extracted from 
other information. 

Methods of Prediction 

In order to develop methods of predicting the char¬ 
acteristics of snow and thus to forecast the perform¬ 
ance of a snow vehicle, the procedure adopted was 
the obvious one of studying the life history of snow 
under various conditions and then determining 
which meteorological factors seemed to be related to 
the physical characteristics of the terrain. 

19 - 3,3 Results 

Physical Characteristics of Snow 

Fhe measurements made as described above 
yielded an abundance of information on the different 
factors selected for study and on the relationships 
between them. Figure 1 gives the penetration-ground 
pressure curves for four types of snow as studied on 
the Saskatchewan Glacier in August and October 



Figure 2. Relationship between snow shearing strength 
and ground pressure, Saskatchewan Glacier, August and 
October 1942. 










320 


SPECIAL STUDIES 



TIME 



pj 


UJ 

48 w 

a: “ 

W H 
46 < 

5 tr 

LlI UJ 

h a 
44 5 

E uj 
< •- 

42 o 


40 


t ^ 

I in 


38 F 



z v 

o t 

h- </> 

<1 Z 

l£ _^ nc( -uJ 
h- ^ 0.65 q 
uj 
2 
UJ 
Q_ 


— 0.60 


0.55 


0.50 



48 uj 
cr 
3 

46 £ 

UJ 

44 5 

UJ 

E- 

42 c 
< 

40 a 


38 F 


Figure 3. Changes in shearing strength, penetration, den¬ 
sity, water content, and air temperature (snow tempera¬ 
ture =32 F) from about 0800 to 1600 hours on bright sun¬ 
shiny day with no winds or clouds, August 3, 1942, on 
Saskatchewan Glacier. 


Figure 4. Changes in shearing strength, penetration, den¬ 
sity. water content, and air temperature (snow tempera¬ 
ture =32 F) from about 1000 to 1600 hours on cloudy, 
moderately windy day after rain preceding evening. Data 
obtained on August 7, 1942, on Saskatchewan Glacier. 


1942. Curve 1 illustrates the penetration in frozen 
firn snow (density about 0.6) found on cold nights 
in August; this type provides the best support for a 
vehicle. Curve 2 represents the penetration in wet 
firn snow (density about 0.5) encountered on a warm 
afternoon in August. Over all such terrain, pilot 
model Weasels sank to a depth of about 2 or 3 inches. 
Curve 3 shows the penetration in heavy powder snow 
(density about 0.25) observed in October, with a 
vehicle penetration of about 4 to 6 inches. Curve 4 
gives the penetration in light powder snow (density 
about 0.17) found in drifts; here the vehicle sank to 
about 12 to 14 inches. 

Figure 2 gives the shearing strength-ground pres¬ 
sure curves for the same four types of snow. It can 
be seen that frozen firn has a very high shearing 
strength and, therefore, may be expected to enable 
a vehicle to climb such terrain at a high angle. Curve 
2 shows that wet firn snow is definitely less resistant, 
although it gains some strength upon compression. 
Curves 3 and 4 show the characteristic behavior of 
light and heavy powder snow encountered on the 
glacier in October. 


The water content of the various types of snow 
was characteristically different, ranging from about 
0 per cent for frozen firn snow, light powder snow, 
and heavy powder snow to about 20 per cent for wet 
fresh snow and 27 per cent for wet firn snow. 

The variations in the characteristics of snow under 
changing atmospheric conditions are illustrated by 
Figure 3, which shows the changes in shearing 
strength, penetration, density, water content, snow 
temperature, and air temperature over about an 8- 
hour period. This figure is based tin the results of 
measurements made on August 3, 1942, on the Sas¬ 
katchewan Glacier on a bright sunshiny day with no 
wind or clouds. Figure 4 presents similar information 
for August 7, 1942, with a cloudy sky, moderate winds, 
and the snow uniformly soft after rain the previous 
evening. 

Correlation with Vehicle Performance 

A study of the varying characteristics of snow and 
of the performance of vehicles operating on snoW 
has indicated that useful correlations can be made. 
This concerns such aspects of performance as climb- 





















PHYSICAL CHARACTERISTICS OF SNOW 


321 


ing ability, penetration, speed, and power consump¬ 
tion. 

Climbing Ability. If a vehicle weighing Q pounds 
and having two equal trac ks each / inches long and m 
inches wide is placed on a slope at an angle 9 to the 
horizontal, then the normal pressure or ground pres¬ 
sure p in pounds per square inch, is given by 

p = 7 r~ cos ^ s 2 cos 6, (1) 

2ml 

while the tangential shearing stress in pounds per 
square inch is given by 

5 = sin (9 = 2 sin 9. (2) 

2m I 

If the vehicle adheres completely and if there is no 
surface gliding between track and snow, the limiting 
angle of climb is given by the shearing strength S of 
the snow on which the vehicle operates. As long as the 
stress s of equation (2) is smaller than the shearing 
strength S, the snow will support the Weasel; as soon 
as s becomes larger than S, the snow underneath the 
vehicle will be sheared off and the vehicle will start 
to slide down the slope. 

In the case of the Weasel, with O about 4,000 
pounds, / 60 to 80 inches, and m 15 to 18 inches, 

sill e = |» (3) 

where S is the shearing strength of the snow under¬ 
neath the tracks. If the shearing strength of the snow 
does not depend very much upon ground pressure 
and if the ground pressure is small (around 1.5 or 
2.0 psi), then it is permissible to identify S with the 
value as measured in the shearing strength apparatus. 
Hence, we may apply equation (3) to determine 
which slopes can be climbed. 

By taking one of the lower shearing strength 
values observed during the test runs, e.g., 0.40 psi, it 
is evident that sin 9 = 0.20, which corresponds to an 
angle of climb of about 15 degrees. Such slopes were 
found to be those on which the Weasel began to fail 
if the snow were soft and weak. 

Equations (1) to (3), however, describe highly over¬ 
simplified cases. The most important factor is the de¬ 
pendence of the shearing strength on ground pressure. 
This can be included by putting 


S = a + bp", (4) 

where a represents the shearing strength without any 
ground pressure and may therefore be called the co¬ 
hesion of the snow; and where b and a are two em¬ 
pirical constants which together characterize the 
behavior of the individual snow sample under con¬ 
sideration. In the case of Huffy, wild snow, a is about 
0.20, and in the case of very soft, heavy snow, it 
increases to only about 0.30. For hard, heavy snow, 
however, it assumes values between 0.80 and 2.00. 
Probably a is rarely less than 1.00 or greater than 2.00. 
In heavy snow, either soft or hard, a is about 1.00 and 
in such cases b is small—0.05 or 0.10—and conse¬ 
quently the ground pressure does not appreciably 
affect the shearing strength. For fluffy, wild snow with 
« about 0.20, b is about 0.50, which indicates that 
ground pressure increases the shearing strength and 
that the second term in equation (4) is most im¬ 
portant. 

In order to get a more general estimate of the 
limiting angle of climb, the equivalent of p in equa¬ 
tion (1) may be introduced into equation (4), giving 
for the shearing strength of the snow underneath 
the vehicle 

s = a + b (Jki cos0 )' (5) 

If a is about 1.00 and the value of b is small, the 
terrain is heavy snow, soft or hard, as treated in equa¬ 
tion (3). For wild snow, it appears that the vehicle 
will just fail to climb when the shearing stress j 
which it produces [equation (2)] equals the shearing 
strength S [equation (5)], as indicated in equation 
(6): ^ 

■fil sin 9 = a -f b (cos A (6) 

2 ml \2 ml / 

If the snow is very fluffy and the ground pressure 
no greater than 1.5 to 2.0 psi, the value of a (0.20) at 
the side of the second term can be neglected. Thus, 


Comparison of equations (2) and (7) shows that 
on heavy snow the climbing potential decreases as 
ground pressure increases—an obvious relationship, 
since it is assumed that the shearing strength of the 
snow is independent of ground pressure, while the 


T* 









322 


SPECIAL STUDIES 



Figure 5. Hill-climbing ability of snow vehicles in vari¬ 
ous types of snow. (A) Aero-sled. (B) Bombardier, (E) Elia- 
son toboggan, (LS) large Archimedean screw vehicle, (SS) 
small Archimedean screw vehicle, (W) Weasel. 

shearing stress decreases with decreasing ground pres¬ 
sure. On fluffy snow, however, the limiting angle of 
climb increases with ground pressure, because the 
precompression solidifies the structure of this type of 
snow and increases its shearing strength. 

Calculation of theoretical maximum climb based 
on the foregoing equations gave results which did 
not deviate significantly from the actual perform¬ 
ance of the Weasel on the Saskatchewan Glacier. It 
seems possible, therefore, to prepare curves of climb 
performance in which the maximum angle of climb 
for a vehicle is plotted against the type of snow on 
which it operates. Such curves are given in Figure 5 
for the Weasel and for five other vehicles tested at 
the same time under the same conditions. The classi¬ 
fication of the various snow types is oversimplified 
but includes those which are likely to be encountered 
most frequently. 

Penetration. In various types of snow, the Weasel 
was found to penetrate from 0 inches on supporting 
crust to 20 inches or more. The depth of penetration 
as such does not appear to affect the rolling ability of 
the vehicle, but the penetration necessary to com¬ 
press the snow to support the unit vehicle weight 
contributes significantly to rolling resistance on the 
flat and increases the net angle of climb by the angle 
of the rut to the slope. This rut angle has varied from 



Figure 6. Maximum speed on level of snow vehicles in 
various types of snow. (A) Aero-sled, (B) Bombardier, (E) 
Eliason toboggan, (LS) large Archimedean screw vehicle, 

(SS) small Archimedean screw vehicle, (W) Weasel. 

4 degrees at 10-inch penetration on a 19-clegree slope 
to 12 degrees at 5-inch penetration on a 24-degree 
slope. Computed variations in ground pressure were 
not found to agree with the penetration actually ob¬ 
served with various types of vehicles in motion. 

Speed. Maximum speed on level ground was found 
to be closely connected with the depth of track pene¬ 
tration and with the compression of the snow. Al¬ 
though these factors were not considered suitable 
for a thorough theoretical treatment in this investiga¬ 
tion, it was possible to prepare speed performance 
curves on the basis of actual measurements on differ¬ 
ent types of snow. These speed curves, similar to the 
hill-climbing curses in Figure 5, are presented in 
Figure 6. 

Power Consumption. An analysis of the power re¬ 
quirements for such a vehicle as the Weasel moving 
on snow has shown that penetration and speed are 
the two most important factors inflencing power 
consumption. 

Prediction of Vehicle Performance 

In order to make maximum use of the correlations 
established between the physical characteristics of 
snow and vehicle performance, it was necessary to 
develop methods for both long- and short-range pre¬ 
diction of vehicle performance. This involved first a 











PHYSICAL CHARACTERISTICS OF SNOW 


323 


study oT the characteristic setting mechanisms under¬ 
gone by freshly fallen snow exposed to various 
weather conditions, and second a study of “typical 
daily fluctuations” which a given type of snow may 
undergo during a day of given weather conditions. 

A review of the measurements obtained, particu¬ 
larly of those made at Camp Hale, indicated that 
certain typical mechanisms could be established for 
the setting of snow. These mechanisms depend upon 
the prevailing weather conditions and are related to 
certain characteristic types of setting. From the ob¬ 
servations obtained, the following mechanisms seem 
important: 

1. Cold weather setting through evaporation. 

2. Cold weather setting through wind action. 

3. Warm weather setting through superficial melt- 
ing. 

As long as any of these mechanisms prevails over a 
given period, it appears that the general properties 
of a snow may be predicted with a fair degree of accu¬ 
racy over a period of several days. 

Even with some overlapping between two of these 
mechanisms, it may still be possible to make reason¬ 
able predictions as long as the weather conditions 
during the critical period are known. If a snow layer 
has been sufficiently characterized by appropriate 
measurements, it appears possible to predict its daily 
fluctuations with fair accuracy if the meteorological 
conditions during the day can be forecast accurately. 
The properties of the snow can then be predicted 
with the aid of empirical fluctuation curves for 
typical days, such as “calm, cold day,” “windy, cold 
day,” “warm, cloudy day,” or “warm, sunny day.” 

Long-Range Prediction 

From the point of view of shearing strength and 
compressibility, it is important to know whether 
settling at subfreezing temperatures occurs in any 
given case preponderantly by evaporation or by 
drifting. It evaporation plays a major role, a snow 
layer gains little in mechanical strength while it con¬ 
solidates, because sublimation produces holes and 
cavities between snow particles and the material is 
not appreciably reinforced. On the other hand, if 
drifting is considerable during settling in subfreez¬ 
ing weather, it may be expected that a wind crust 
will appear, increasing the shearing strength and 
decreasing the compressibility of the layer. 

Measurements at Camp Hale indicated that if cold, 


dry weather with moderate wind is expected, it is 
reasonable to predict that (1) density will increase 
very slowly, (2) evaporation will keep die snow fluffy, 
(3) no crust formation will occur, and (4) the shear¬ 
ing strength will remain very low (less than 0.8 psi at 
2.0-psi ground pressure). Such conditions are highly 
adverse for the operation of a snow vehicle. If this 
type of settling occurs frequently or continuously, 
unfavorable conditions may last for many weeks. 

On the other hand, if meteorological conditions 
indicate a period of cold, moist weather with mod¬ 
erate or considerable wind, Camp Hale studies 
showed that (1) the density of the snow will increase 
relatively quickly, (2) there will be little or no evapo¬ 
ration, (3) the snow will set faster, (4) crusts will 
form, and (5) shearing strength will increase (gener¬ 
ally up to about 1.5 psi at 2.0-psi ground pressure). 
Snow setting under these conditions provides rela¬ 
tively favorable terrain for vehicle operation and 
after one week or so leads to what has often been 
termed “ordinary winter snow.” This is a snow layer 
2 to 5 feet deep with an average density between 0.20 
and 0.30, a comparatively strong crust, and a shearing 
strength between 1.5 and 2.5 psi at 2.0-psi ground 
pressure. 

The third type of setting—that which occurs in 
warm weather—seems to involve melting as a main 
process, with the uppermost layer melting during the 
hours when the temperature is above zero and with 
the liquid draining down and refreezing as soon as it 
reaches the colder layers underneath. After a certain 
amount of snow is removed in this way from the top 
layer, the rest of the layer collapses and forms a new 
and somewhat denser structure. This structure freezes 
during the hours of subzero temperatures to give the 
familiar snow crust or melt crust which marks this 
type of setting. Snow exposed to these conditions is 
generally characterized by an increase in shearing 
strength and by a decrease in penetration. 

Figure 7 illustrates the changes in density of snow 
exposed to different loads over a 10-day period. As 
it was expected, increased loads give a radically 
greater density. 

Short-Range Prediction 

A survey of the Camp Hale results on daily fluctua¬ 
tion in snow properties indicates that on typical 
“cold winter days” the shearing strength is lowest in 
die morning, rises slightly during the day, reaches a 
maximum plateau at about 1800 hours, and drops 


Xaa ^fOTNTFV l, 





SHEARING STRENGTH PSI DENSITY 


324 


SPECIAL STUDIES 




Figure 8. Typical “cold winter day” changes in shearing 
strength of snow over 24-hour period. 



Figure 9. Typical “mild spring clay” changes in shearing 
strength of snow over 24-hour period. 

(XLNJ 


down again during the night (Figure 8). During 
“mild spring days,” it is virtually impossible to make 
even approximate predictions, because these are too 
dependent upon uncontrollable local conditions 
(Figure 9). On “clear, cool spring days” and “clear, 
cool summer days,” the shearing strength is very high 
in the early morning, decreases as the sun becomes 
more and more effective, reaches its minimum in the 
early afternoon, and then rises to reach its maximum 
value after midnight (Figure 10). 

Prediction of Climbing Ability 

A further empirical method was developed for 
predicting the maximum climb of a vehicle from the 
depth of the last snowfall and the air temperature 
since the last snowfall. A diagram given in Figure 
11 makes it possible to indicate that if, for example, 
21/9 feet of snow have fallen several days before and 
if, since then, the average temperature has been about 
28 F, maximum climb of the vehicle will be between 
17 and 18 degrees. Only a limited number of meas¬ 
urements were made during this study to support 
i his method of prediction, but it seems to have a fairly 
sound general background. 

'9-4 WAKE VISIBILITY AND ITS 
SUPPRESSION 

Summary 

In an attempt to reduce the visibility of the wakes 
of small amphibious vessels used in landing opera¬ 
tions, tests were conducted on chemical mixtures and 
mechanical baffles proposed as wake-suppressors. Un¬ 
der the conditions of the tests, none of the mixtures 
or devices was found to possess any practical value. 

19 4-1 The Problem 

The wake of a moving vessel is generally its most 
conspicuous feature and may be detected under some 
conditions at distances at which the ship itself is 
practically invisible. In operations in the Southwest 
Pacific, for example, pilots reported detecting vessels 
by their wakes, particularly on moonlit or clear star¬ 
lit nights, with or even without phosphorescence. 

As part of a study f of the use of such vehicles as the 
DUKW in amphibious landing operations in com¬ 
bat areas, it was desirable to investigate the wakes of 


f See Chapters 3 and 4 in this volume. 

















WAKE VISIBILITY AND ITS SUPPRESSION 


325 



Figure 10. Typical “clear cool spring or summer day” 
changes in shearing strength of snow over 24-hour period. 


small craft, the conditions under which these wakes 
might be most easily detected, and the use of various 
oils, dyes, spreading agents, smokes, and mechanical 
baffles proposed as wake-suppressors. 8 

g This investigation was conducted by the Woods Hole 
Oceanographic Institution, Woods Hole, Mass. 


I9 - 4 - 2 Procedure 

With the exception of brief and preliminary ex¬ 
periments at Woods Hole, Massachusetts, the major 
part of the investigation was conducted in Florida 
waters near Fort Pierce, Cocoa Beach, and the Banana 
River in February and March 1943. One DUKW was 
used to carry the experimental equipment and oper¬ 
ated with another DUKW acting as a control. Usually 
the two vehicles moved abreast on parallel courses 
about 900 feet apart. The DUKWs and their wakes 
were studied, and photographed where possible, by 
observers located at sea level, in shore towers, and in 
aircraft flying from nearly sea level to an altitude of 
10,000 feet. Runs were made both in daytime and at 
night. 

Foam Suppressor 

Special foam suppressor equipment was installed 
on the experimental DUKW to spray streams of vari¬ 
ous mixtures from the bow and stern (Figure 12). 
These mixtures included: (1) Diesel oil and sea water, 

(2) Diesel oil, sea water, and a spreading agent, 1 ' and 

(3) solutions of dyestuffs. 1 

h Palmetic acid, oleic acid, stearic acid, diphenylamine, and 
ociyl alcohol were tested in turn, in concentration of 1 per cent 
by weight. 

i Calco Chemical R 1616-22-1 and R 1616-22-2. 



Figure 11. Curves for prediction of maximum Weasel hill-climbing performance in snow. 


































































































































































































326 


SPECIAL STUDIES 



Figure 12. Use of foam suppressor equipment on experimental DUKW (lower). Woods Hole, Massachusetts. 


Baffles 

In order to reduce the visibility of the bow spray 
and of the stern geyser, a canvas bow curtain was 
hung from a hoop extending over the bow, and a tar¬ 
paulin was towed from the stern (Figure 13). Later, 
in order to prevent excess air from being drawn 
under the DUKW stern, a horizontal baffle was 
placed across the full width of the stern just below 
the water level. 

1943 Results 

It was found that the foam suppressor, using Diesel 
oil alone or with mixtures of other agents, does re¬ 
duce surface foam but does not appreciably reduce 
air spray or clouds of air bubbles, which appear down¬ 
stream beneath the surface (Figure 12). The bow cur¬ 
tain and stern tarpaulin reduce air spray, but the sur¬ 
face foam remaining in the wake is not significantly 
affected (Figure 13). 32 

Tests performed in the Banana River clearly indi¬ 
cated the difficulty of suppressing wake visibility in 
turbid and foamy water (Figure 14). 

The results of air observation are shown in Figure 
15, which includes vertical and oblique views taken 
at altitudes up to 10,000 feet and at distances up to 
4 miles. In each case, the experimental DUKW was 


equipped with a bow curtain, a stern tarpaulin, and a 
foam suppressor spraying a mixture of Diesel oil and 
salt water from bow and stern. In this series, the nor¬ 
mal DUKW was painted khaki and the experimental 
DUKW, blue. 

A general survey of the results showed that in day¬ 
time observations from the surface the hull is usually 
more obvious, especially if it is seen against the hori¬ 
zon, but that from the air the wake can be distin¬ 
guished for many miles beyond the point at which the 
hull becomes invisible and is not only the most im¬ 
portant but often the only feature revealing the pres¬ 
ence of the vessel. 

In night observations from sea level, the hull is 
more conspicuous with moonlight or bright starlight, 
while the wake is more distinguishable with strong 
phosphorescence. In night observations from the air, 
the relative importance of hull and wake varies 
greatly according to the circumstances. Thus, on 
moonlight nights, the hull can be distinguished for 
several miles and is more conspicuous than the wake; 
on dark nights, or with only moderate phosphores¬ 
cence of the water, the wake is usually seen first; with 
strong phosphorescence, the wake may reveal the 
presence of a vessel from a distance of several miles; 
and on dark nights with no phosphorescence, neither 
hull nor wake can generally be seen. 



Figure 13. Use of bow curtain and stern tarpaulin on experimental DUKW (lower), Woods Hole, Massachusetts. 














WIND AND WAVE STUDIES 


327 


19 4 4 Recommendations 

The installation of foam suppressor equipment, 
particularly on the DUKW, was not recommended. 
The use of a bow curtain and stern tarpaulin might 
have some camouflage value against visual observa¬ 
tion close to sea level. Further investigation might be 
profitably undertaken on the use of other baffles and 
on the use of black smoke to reduce the visibility of 
subsurface bubbles. 

If further investigations should be undertaken in 
this field, they should be directed toward the suppres¬ 
sion of wake visibility by daytime observations from 
the air and by night observations from either air or 
sea level during conditions of moderate or strong 
phosphorescence, in which the wake is usually more 
conspicuous than the hull and in which suppression 
would have most practical value. 

195 WIND AND WAVE STUDIES 
Summary 

Measurements of wind velocity, wave height, wave 
period, wave length, and the velocity of propagation 
of waves, followed by a correlation of these measure¬ 
ments, have made it possible to predict wave heights 
from wind velocities with reasonable accuracy in 
deep water as well as in coastal waters under certain 
conditions. 

In currentless deep water, the wave height meas¬ 
ured in feet is about 0.5 times the velocity in mph of a 
persistent wind. In coastal shoal water, the wave 
height in feet is about 0.3 times the wind velocity 
in mph. 

19 - 51 The Problem 

As part of the development and investigation of 
the DUKW and other amphibians intended for oper¬ 
ation in surf and open sea, it was recommended by 
Division 12 late in 1942 that a brief study be under¬ 
taken on the relationships between wave character¬ 
istics and wind velocity. j 

I9 - 5 - 2 Procedure 

From November 10 to December 7, 1942, observa¬ 
tions and measurements were made off Provincetown, 

j This investigation was conducted by personnel of Division 
12 of NDRC and of the Brooklyn Polytechnic Institute, Brook¬ 
lyn, N. Y. 



Figure 14. Effect of foam suppressor equipment on ex¬ 
perimental DUKW' (lower), in foamy, turbid water. 
Banana River, Florida. 


Massachusetts, on the characteristics of waves at dif¬ 
ferent wind velocities. 

Wind velocity was measured with two permanent, 
recording anemometers elevated high above water 
level and with two hand anemometers, all calibrated 
to give identical readings under identical conditions. 

Wave height was measured from shore by transit 
observation of floating wooden blocks fastened on 
anchored barges 200 to 800 yards from the beach and 
equipped with long vertical bamboo rods marked 
with a foot scale. The height or amplitude of a wave 
was defined as the vertical distance between the low¬ 
est and highest points marked on the rods. Ampli¬ 
tudes up to 9 feet were measured in this manner, and 
even greater values up to 12 feet were estimated with 
a telescope by noting the up and down movements of 
vessels of known dimensions (lighters, freighters, 
DUKWs, etc.) standing farther out to sea. 

Wave period was determined with similar equip¬ 
ment by noting the time for a floating mark to make 
20 full oscillations. The longest period measured was 
5.5 seconds. 

Wave length was never measured accurately, but 
cotdd be estimated on several occasions. In some cases 
the length of a wave could be judged by observing it 
as it travelled along the side of a ship with a known 
length, and in others by standing on a protruding 
point of land and looking through a transit or tele¬ 
scope perpendicularly to the direction of wave mo¬ 
tion some hundred yards offshore. The greatest 
lengths observed in this study were between 80 and 
90 feet. 











328 


SPECIAL STUDIES 




B 

E 



X 

CONTROL 

EXPERIMENTAL 

DUKW 

DUKW 

V 


\ 

Experimental 


DUKW 

CONTROL 


DUKW 



CONTROL 

DUKW 


X 


EXPERIMENTAL 

DUKW 



Figurf. 15. Air observation of wakes, Atlantic Ocean east of Banana River Naval Air Station. Florida. (Experimental 
DUKW equipped with foam suppressor equipment, bow curtain, and stern tarpaulin. 


A. Observer 1,000 feet above DUKWs. 

B. Observer 5,000 feet above DUKWs. 

C. Observer 10.000 feet above DUKWs 


D. Observer 1 mile north of DUKWs at 1.000 feet. 

E. Observer 2 miles north of DUKWs at 5,000 feet. 

F. Observer 4 miles north of DUKWs at 10.000 lect. 









WIND AND WAVE STUDIES 


329 



Figure 16. Factors involved in the correlation of wind 
velocity with characteristics of waves in deep water. 


Likewise, the velocity of propagation of leaves 
coulcl not be measured accurately but was estimated 
by observing with a transit or telescope the move¬ 
ment of the crest of a wave under an oblique angle. 
A certain distance of travel was then marked with a 
stop watch and the velocity estimated. Rates up to 
20 mph were roughly determined in this way by 
means of this method of estimation. 

19 - 5 - 3 Results 

For a wave in deep water and under steady condi¬ 
tions (depth larger than wave length, far offshore), 

v=ft (8) 

*-.7r 

and l = ~-t 2 (9) 

Ztt 

where v — wave velocity, I = wavelength, t = period, 



Figure 17. The effect of wind velocity on wave height in 
coastal waters. 


and g = gravity. If v is expressed in mph, / in feet, and 
/ in seconds, 

v = 3.8 / (10) 

and / = 4.8* 2 (11) 

Figure 16 shows diagrammatically the conditions in¬ 
volved and defines the quantities under considera¬ 
tion. Equations (10) and (11) have been frequently 
checked by other workers and found to be reliable, 
provided that the depth of the water is much greater 
than the wave length, that the wind direction and 
velocity remain steady, and that no obstacles are en¬ 
countered. 41 Periods up to 16 seconds have been ob¬ 
served in the open sea of the South Atlantic and South 
Pacific. These periods correspond to a propagation 
velocity of 57 mph and a wave length of 1,080 feet. 

No fundamental theoretical relationships exist be¬ 
tween wave velocity v and wind velocity iv, nor 
between wave height h and wave period t. Very ex¬ 
tensive observations, however, have established two 


Table 1. Fundamental Relationships of Steady Waves in Deep Water. 


IV 

in mph 

V 

in mph 


h 

in feet 


I 

in feet 


t 

in seconds 


ohs. 

calc. 

obs. 

calc. 

obs. 

calc. 

obs. 

calc. 

23 

16 

17.5 

8 

11.0 

90 

106 

4.0 

4.6 

25 

19 

19.0 

11 

13.0 

115 

125 

5.2 

5.0 

30 

25 

22.8 

14 

14.4 

190 

180 

6.0 

6.0 

45 

35 

34.2 

23 

21.6 

400 

405 

8.8 

9.0 

50 

39 

38.0 

28 

24.0 

440 

500 

9.5 

10.0 

75 

58 

57.0 

37 

36.0 

1.080 

1.125 

16 

15.0 






































SPECIAL STUDIES 


330 



3.0 4.0 5.0 6.0 

WAVE PERIOD t IN SECONDS 

Figure 18. Wave height as a function of wave period. 


28 


24 


20 


16 


2 
JC 
I- 
X 
(D 

X 12 

iLl 

I 


/ 

/ 


7* 

/ A 

// 

/ / 

// 

A /~7 


A 


, DEEP WATER, 
/ STRONG WINDS 




/ 


COASTAL WATERS, MODERATE WINDS 


10 


20 30 

WINO VELOCITY w IN MPH 


40 


50 


Figure 19. The effect of wind velocity on wave height in 
coastal waters and in deep water. 


empirical relationships which seem to hold fairly 
satisfactorily if the conditions mentioned above are 
fulfilled. These are 


v = 0.76 zu 

(12) 

h = 2.4 t = 0.48 xu. 

(13) 


where zu and v are measured in mph, h in feet, and t 
in seconds. 

Waves in Deep Water 

The measurements obtained by the methods de¬ 
scribed above are given in Table 1, together with the 
values derived from equations (10), (11), (12), and 
(13). It appears that these equations are reasonably 
valid and most closely approach the observed values 
for the larger waves, which is to be expected since 
large waves are less susceptible to any kind of pertur¬ 
bation. The first line in the table, referring to a mod¬ 


erate wind velocity of 23 mph and a correspondingly 
small wave, shows a significant deviation of the ob¬ 
served from the calculated values. It seems, therefore, 
that although they are valid for strong wind and large 
waves way offshore, these relations must be somewhat 
modified to apply to more moderate wind and smaller 
waves—the characteristics of coastal waters. 

Waves in Coastal Waters (30-200 Feet Deep) 

From data obtained in measurements in 30- to 
200-foot water nearer the shore, it appeared possible 
to extend equations (10) to (13) in order to cover these 
different conditions. The new relations are 


II 

o? 

o 

+1 

II 

(0.74 ± 0.02) zu, 

(14) 

/ = (2.6 ± 0.4) /-’ = 

(0.12 ± 0.03) zu 

(15) 

h = (1.5 ± 0.3) / = 

(0.32 ± 0.05) zu, 

(16) 

zu = (4.6 ± 0.2) t. 


(17) 


Table 2. Correlation of Wind and Waves in Coastal Waters. 


zu 

in mph 

V 

in mph 

h 

in feet 

l 

in feet 

t 

in seconds 


obs. 

calc. 

obs. 

calc. 

obs. 

calc. 

obs. 

calc. 

to 


7.2-7.6 

2.5 

2.7-3.7 

10-12 

10-15 

2.5 

2.2-2.4 

12 

10 

8.6-9.0 

3.0-3.5 

3.2-4.2 

10-16 

14-22 

3.0 

26-2.9 

14 


10.1-10.5 

4.0-5.0 

3.7-1.7 

25-30 

17-26 

3.8 

3.1-3.1 

16 


11.5-12.0 


4.3-4.8 

30-35 

25-35 


3.5-3.8 

18 

13 

13.0-13.5 

4.5-5.0 

4.8-5.8 


33-50 

4.2 

4.0-4.3 

20 


14.4-15.0 

6.0-7.0 

5.4-7.4 

35-55 

40-60 

4.5 

4.4-46 

22 


15.8-16.5 

6.0-8.0 

6.0-8.1 

60-70 

48-72 

5.0 

4.8-5.3 

24 

16 

17.3-18.0 

8.0 

6.5-8.8 


57-85 


5.3-5.8 

26 


19.0-20.0 

7.5-9.0 

7.0-9.5 

70-80 

67-100 

5.5 

5.7-6.2 

28 


21.0-21.5 

7.5-9.5 

8.0-10.0 


79-120 

6.0 

6.0-6.7 

30 


22.8 

9.5-10.0 

9.0-11.0 

115 

90-135 

6.0 

6.1-7.2 











WIND AND WAVE STUDIES 


331 


The summarized results of the measurements in 
coastal waters, together with the predicted values ob¬ 
tained from these empirical equations, are given in 
Table 2. As far as could be determined, equations (14) 
to (17) hold with reasonable accuracy under the fol¬ 
lowing conditions: 

1. The wind must blow for more than 1 hour with¬ 
out changing in intensity or direction, and without 
being hindered by dunes or other obstacles. 

2. There must be no coastal current or strong tide 
interfering appreciably with the waves produced by 
the wind. 

If these conditions are fulfilled, equation (16) per¬ 
mits the prediction of the average height of the waves 
as a function of the wind velocity. This is shown 
graphically in Figure 17, with the two dotted lines 
representing the calculated limiting values, and the 
points showing some of the measured values. Simi¬ 
larly in Figure 18, wave height is shown as a function 
of wave period. Since u' and t can be rather easily 


measured, the two graphs provide a method of pre¬ 
dicting wave height. 

Figure 19 illustrates the combination of these rela¬ 
tionships, with equation (16) used for moderate wind 
velocities—0 to about 30 mph—in coastal waters, and 
equation (13) for higher wind velocities—about 25 to 
50 mph—in deep water. 

19-5 - 4 Conclusions 

Two sets of equations have been found useful in 
predicting wave height from wind velocities over a 
range of 10 to 50 mph with reasonable accuracy. One 
set of equations, previously established by earlier 
work for large waves in deep water offshore, gives 
values corresponding closely with observed values ob¬ 
tained in this study. Another set of equations empiri¬ 
cally established in this investigation for smaller 
waves in coastal waters was found to yield satisfactory 
predictions of the limiting values of wave height. 41 






Chapter 20 

SPECIAL PROJECTS 


20-1 10-TON MISSILE* 

Summary 

I n an attempt to develop a large missile which could 
be used to destroy main Japanese fleet units at 
anchor and to breach Japanese dams, a 10-ton bomb 
was designed for delivery by means of a B-17 Flying 
Fortress bomber. The bomber may be operated by a 
skeleton crew or equipped with television and oper¬ 
ated by remote control from a B-29 Superfortress 
bomber flying beyond range of enemy fire. 

Plans for these devices, together with the results 
of scale tests, were presented to the U. S. Navy in July 
1944 and to the Army Air Forces in September 1944. 
The project was abandoned, however, because of 
lack of interest by the using branches of the Armed 
Services. 

20 11 The Problem 

In the summer of 1944, with the Japanese fleet 
reluctant to leave port and with invasion of the 
Japanese home islands imminent, the director ol 
the Office of Scientific Research and Development 
[OSRD] requested an investigation of methods which 
could be used to destroy main enemy fleet units lying 
in harbors and to attack certain important enemy 
dams. b 

2012 Procedure 

A preliminary consideration of available low- 
angle glide bombs and small drones showed that 
these devices could not deliver an effective one-shot 
charge, and on a multiple-shot, “dry” hit basis would 
be subject to the disadvantage of relatively low veloc¬ 
ity. The available evidence on successful operation 
for aerial homing devices was not impressive. 

Attention was therefore centered on the possibility 
of using very large drones, each carrying a massive 

a Project “Egg.” 

b This investigation was supervised by a representative of 
Division 12 of NDRC, assisted by the Applied Mathematics 
Panel and the Douglas Aircraft Corporation, and conducted 
largely by the California Institute of Technology, Pasadena, 
Calif. 


charge and controlled from a large “shepherd” plane 
by means of television, radar, and related devices. 
As an alternate plan, in view of the probable compli¬ 
cations and delays involved in attempting to deliver 
a single large charge by a drone, a study was made 
of the possibility of delivering the charge in a low- 
altitude surprise attack with a stripped plane carry¬ 
ing a minimum crew and usinga low-level bombsight. 



Figure 1. Scale model of proposed Egg missile. 

A study of the effect of attacks on capital ships 
showed that no non-armor-piercing missile large 
enough to destroy a battleship was available, and 
that a single charge of not less than fi to 7 tons of 
explosive would be required. From available evi¬ 
dence, which was confusing and controversial, it 
appeared that an 8-ton charge would be capable of 
sinking or very seriously damaging a modern battle¬ 
ship. if the charge exploded below the target, the 
resulting force might well break the back of the ship. 

In detonating a given mass of charge in an attempt 
to sink a ship, it was accepted as generally true that 
a “wet” hit is more effective than a “dry” one, for 
the shock waves are more effectively transmitted by 
water and the lower portion of the hull is usually 
more vulnerable. (An obvious exception is the case 
of the charge which penetrates the deck armor and 
explodes inside the ship, but this requires armor¬ 
piercing properties and presumably limits the size 
of the charge.) These considerations lent special at¬ 
tractiveness to a low-level attack with a single large 
charge so delivered and so fused as to give a low “wet” 
hit, and this was made the basis for the design of 
the missile. 




10-TON MISSILE 


333 



■^DETACHABLE NOSE 

SIDE ELEVATION 




Figure: 2. Schematic layout of Egg missile. 


o 

SECTION A-A 


o 

SECTION B-B 


20,1,3 Results 

The Missile 

The missile designated as the Egg is a bomb carry¬ 
ing a 20,000-pound charge in a body 22 feet long, 
consisting of a cylindrical section 44 inches in diame¬ 
ter and 6 feet long, and followed by a frustum of a 
cone 16 feet long with a diameter of 21 inches at the 
small end (Figures 1 and 2). The bomb is provided 
with a detachable nose fairing, tail fairing, and sta¬ 
bilizing surfaces, making the over-all length about 
35 feet. 

The nose fairing is needed to avoid flow separation 
at the sharp edges on the front of the charge and to 
prevent high drag and doubtful stability. The fairing 
would be built of thin or brittle material so that it 
would break up on impact with the water and not 
influence the underwater characteristics of the 
charge. The tail would likewise break off on contact 
with the water. Its purpose is to guide the bomb into 
the water at an angle within the limits necessary for 
proper underwater trajectory. Stability in pitch is 
provided by a horizontal tail, and stability in yaw 
by twin vertical tails mounted at the tips of the hori¬ 
zontal stabilizers. 

Several models of this design were built to a scale 
of 1:32 and tested for stability and for type of under¬ 
water trajectory. These indicated that a full-scale 
unit could be built so that, at an entrance velocity 
of 300 to 400 fps, it would slow to 200 fps in 65 feet 
of underwater travel, and would travel 200 to 225 
feet under water at a maximum depth of orbit of 30 


feet for a 17i/2-degree entry angle. The orbit would 
not be appreciably affected by pitch angles of entry 
of ±2 degrees. The trajectory would not be affected 
by shallower entry angles as small as 12 degrees, but, 
for larger entry angles up to 22 degrees, the maxi¬ 
mum depth of orbit might be slightly increased be¬ 
yond 30 feet. 5 

A survey of facilities available to the California In¬ 
stitute of Technology showed that California manu¬ 
facturers, with stock in hand and without priorities, 
could deliver substantial numbers of Egg missiles in 
60 days. 

The Missile Carrier 

The B-17 Flying Fortress bomber can be readily 
modified to carry the 10-ton missile designed for this 
project (Figure 3). ft would be stripped of all unnec¬ 
essary equipment, particularly the turrets and the 
turbo-superchargers. The power plant could be 
modified to give more power by incorporating a 
water injection system with water tanks, water 
pumps, and carburetor de-enrichment devices, and 
by adding jet exhaust stacks and one or more gas 
turbines in the rear of the fuselage. 

Without armament or turbos, but with the 10-ton 
missile attached, the B-17 would require about 18,000 
pounds of fuel for an 1,800-mile absolute range at 85 
per cent rated power at 10,000 feet. This would give 
an average speed of approximately 210 mph and a 
take-off weight of approximately 72,000 pounds. The 
take-off distance to a 50-foot height would be approxi¬ 
mately 6,000 feet with 4,800 blip for take-off. 4 








































334 


SPECIAL PROJECTS 



Figure 3. Egg missile in place under B-17 Flying Fortress. 


Use Against Ships 

The delivery of the Egg is visualized as a minimum 
altitude attack—perhaps from 100 to 300 feet above 
sea level—by a cleaned-up B-17 manned by a two-man 
crew. It is not planned as a suicide mission. Instead, 
the specification of a small crew connotes that arma¬ 
ment has been exchanged for speed and pay load. It 
would be used in a surprise attack, or in a task force- 
supported operation in which smoke and other anti¬ 
flak techniques are used to get the B-17’s in and out 
again. 

In a surprise attack, the aircraft would have suffi¬ 
cient fuel to reach a surface rendezvous, perhaps with 
a submarine, or to return to base. In an attack made 


in concert with a task force, the aircraft can rendez¬ 
vous with units of the force. 

For attacks in which visibility is adequate, the 
low-altitude, angular-rate Mark 23 bombsight is sug¬ 
gested, since it can presumably establish the point 
of entry with a probable error of approximately 25 
feet. If the target is not visible, a simple radar bomb¬ 
ing aid would be used. 

As an alternate method, the Egg could be delivered 
in a B-l 7 under remote control of a “shepherd” plane, 
such as a B-29 Superfortress bomber. This would re¬ 
quire equipping the B-17 with suitable television 
and remote-control devices, and although many if 
not all of the essential items could be obtained 






10-TON MISSILE 


335 



Figure 4. Path and site of explosion of proposed Egg missile. 


quickly, a considerable and lengthy development 
would be involved in joining them into a dependable 
operating system. 

As another alternate method, consideration was 
given to the possibility of having the remote-con¬ 
trolled B-17 crash into the ship’s side, with the 
charge exploding immediately as a “dry” hit or, after 
the wreckage of the B-17 had sunk, with the bomb 
going off under water as a “wet” hit. This plan was 
not recommended because of the limited effectiveness 
of such a “dry” hit, the complications involved in 
transforming this into a “wet” hit, and the added 
vulnerability of the B-17 to enemy antiaircraft fire. 

In the first two proposals, it is planned to fuse the 
bomb so that it would explode only after it had struck 
the ship’s side and sunk to a point below the target’s 
keel (Figure 4). In such a position, the effect of the 
charge would reach its maximum. 

Use Against Dams 

The Egg would be used similarly in attacks against 
a dam, with the expectation that a contact explosion 
of the 10-ton bomb would produce a 20-foot crater 
in the wet face. An extrapolation based on experi¬ 
ence with earth-backed fortifications indicates that 
the tensile and shear strengths of a dam may be ex¬ 
ceeded if the Egg is detonated within about 40 feet 
of the dam face at a depth of about 40 feet, the water 
level being within 10 feet of the top. 

On the basis of the British attacks on the Moehne 
dam in Germany, it appears that the proposed 10- 


ton missile would be more practical. The British 
bombs had to be dropped within a 30-foot space to 
give a successful and not premature detonation. Be¬ 
cause of the long underwater travel of the Egg, it 
would have to be dropped within a 150-foot space. 

A high-altitude attack does not seem to be feasible 
for attacks on dams. 

Use of Other Missiles 

Although none would fill the requirements of a 
single-charge destructive missile, several devices may 
be investigated further. These include the AZON 
converted to an armor-penetrating projectile; low- 
angle glide bombs; and ROC and RAZON modified 
for shaped charges or for armor penetration. 

20 14 Conclusions 

Although no final recommendations could be 
made on the relative merits of high- and low-altitude 
bombing, or of one-shot attacks, it appeared from 
this preliminary study that the 10-ton missile should 
be developed and tested, and that the associated 
problems, including mounting and release mecha¬ 
nisms, optical and radar low-level bombsights, and 
the physical characteristics of the explosive to be 
used, should be investigated with all possible prompt¬ 
ness. The alternate method of equipping a plane for 
remote-control delivery of the Egg should likewise 
be examined in more detail. Investigations should be 


CG ^rm^TT AL 

















336 


SPECIAL PROJECTS 


continued on the modification of existing smaller 
missiles for this particular objective. 

20.2 JOINT PROJECTS 0 

In May 1943, the Army and Navy jointly requested 
NDRC to investigate navigational aids which could 
be used in landing operations and to study methods 
for the demolition of obstacles to such operations. 
The Chairman of NDRC appointed personnel of 
Division 12 to serve with Committee NALOC (Navi¬ 
gational Aids for Landing Operations) and Commit¬ 
tee DOLOC (Demolition of Obstacles to Landing 
Operations), set up to meet this military request. The 
work of these ad hoc committees is summarized in 
the final reports submitted by them. 

In the development of the atomic bomb under the 
Manhattan Project, Division 12 was represented by 
Hartley Rowe, Chief of the Division, who was ap¬ 
pointed consultant to the Chairman of NDRC for 
duties with the director of the research laboratory at 
Los Alamos, New Mexico, and by Roger S. Warner, 
Jr., technical aide of Division 12 and later attached 
to Division 3, who was appointed to aid in develop¬ 
ing, engineering, assembling, and testing the atomic 
bomb. Later Warner was sent to the Pacific theater 
to assist in assembling the bomb that was dropped 
on Nagasaki and was present as an observer aboard 
the B-29 that dropped the bomb. 

20.3 TRANSFERRED PROJECTS 

Early in the history of NDRC, several projects 
were assigned to or initiated by Division 12 or its 
antecedents, Sections C2 and C3, and later, after 
NDRC reorganizations, transferred to other divisions 
or to the Armed Services. Final reports will be found 
in the summary reports of these divisions. These proj¬ 
ects included the following: 

c Projects AN-2 and AN-9: Manhattan Project. 

f i Summary Technical Report, Division 17, NDRC. 


1. A magnetic compass developed for use in tanks 
and other vehicles.' 1 

2. An odograph developed largely as the result of 
research on the magnetic compass.' 1 

3. Methods to protect tanks against antitank land 
mines.' 1 

4. An ultrasilent, gasoline-driven electric gener¬ 
ator which could not be heard in operation at a dis¬ 
tance of 200 yards. e 

5. The development of a group of infrared de¬ 
vices. 6 

6. The development of a small, portable, rugged 
device requested by the Corps of Engineers for use in 
the field to make quick, accurate reproductions of 
maps. A survey of all available processes by Division 
12 led to the selection of the manufacturer 1 who ap¬ 
peared best suited to conduct this investigation. This 
project thereafter operated under direct control of 
the Army, and no report of any results is reported by 
NDRC. 

7. Plans for added defense against the night bomb¬ 
ing of Britain by the enemy. It was proposed by Divi¬ 
sion 12 that a certain proportion of antiaircraft guns 
be devoted during an attack to fire haze-making 
shells. Then, by disposing upward-directed para¬ 
chute flares within and below the haze, it would be 
possible to silhouette the enemy aircraft against a 
luminous background for attack from above, and, 
by placing downward-directed parachute flares above 
the enemy planes, to silhouette them for attack by 
antiaircraft lire from the ground. In order to prevent 
burning the shroud-lines of the parachute flares, it 
was recommended that the flare be mounted on top 
of the parachute, probably being held in place by 
means of a suitable counterweight. 

8. Plans made early in World War II for long- 
range attacks on the Japanese Fleet by means of a 
television-equipped, glider-borne aerial torpedo to 
be towed and radio-controlled by heavy bombers.® 

0 Summary Technical Report, Division 16, NDRC. 

f Charles Binning Company, Inc., Chicago, Illinois. 

s Summary Technical Report. Division 5. NDRC. 






GLOSSARY 


A-FRAME. A two-legged lifting device held in position by guy 
wires. 

AAF. United States Army Air Forces. 

AEF. Allied Expeditionary Forces. 

AFAF. Amphibious Forces, Atlantic Fleet, United Slates Navy. 

AFHQ. Headquarters, Allied Forces. 

AFPF. Amphibious Forces, Pacific Fleet, United States Navy. 

AFTER BREAK. The wall of broken water resulting from the 
collapse of a comber when it reaches shoal water. 

AGF. United States Army Ground Forces. 

AKA. Attack Transport (ship). 

ALLIGATOR (ROEBLING). Early full-track amphibious 
vehicle. 

AMPHIBIOUS JEEP. \/ 4 -ton, 4x4 amphibious truck. 

AMTRAC. See IA’T(4). 

ARK. M-29C amphibious Weasel. 

ASF. United States Army Service Forces. 

BACKSTAY. The rear stay of a mast. 

BALK. A support in the form of a transverse beam. 

4."5 BBR. 4.5-inch beach barrage rocket. 

7."2 BBR. 7.2-inch beach barrage rocket. 

BHD. Bulkhead. A wall to form a division or a compartment in 
a vessel. 

BITT. A fixed deck fitting for securing lines. 

BLONDIN. A cable that supports a net so that, with the assist¬ 
ance of kites and drogues, the net is held in a vertical position 
when moving through the water. 

BOGIE. In a track-propelled vehicle, a wheel through which 
weight is transmitted to the track. 

BOW CELL. Watertight compartment attached to the bow to 
increase buoyancy. 

BOW SCOOP. In a track-propelled amphibian, a device added 
to the standard bowblock extending it along and around the 
track. 

BOW WAVE. Characteristic wave produced in water by a par¬ 
ticular structure of a ship or amphibian bow. 

BOW WING. In a track-propelled amphibian, a device to strip 
water off the forward end of the return track at the center 
line of the sprocket and to turn it 180 degrees outboard and 
astern. 

BOWBLOCK. In a track-propelled amphibian, any device 
placed at the forward end of the return track for the purpose 
of changing the direction of the water leaving the return 
track. 


BRAIL. A line for gathering up a sail or other canvas, or a net. 
To gather up a sail or net. 

BROACHED. Turned broadside to the sea in such a manner as 
to be in danger of swamping. 

BUFFALO. See I.VT(3). 

c. Cycles per second. 

C. Degrees centigrade. 

CAPSTAN. A cylindrical winching device with a perpendicular 
axis. 

CARGO BOW. Support for tarpaulin covering cargo compart¬ 
ment. 

CATAMARAN. A device by which two hulls are held together 
side by side in order to gain additional flotation and stability. 

CAVITATION. The formation of voids or cavities when the 
propeller is turned at such a speed that the tea ter is dis¬ 
charged faster than it can flow into the propeller. 

C.CKW. General Motors Corporation 2i/£-ton, 6x6 truck. 

CENT AC. Central Pacific Command. 

CHINE. In the construction of a certain type of vessel, the edge 
formed at the intersection of the bottom and side of the vessel. 

CHORD. In bridge building, the upper and lower members of 
a truss. 

CINCPAC. Commander in Chief, Pacific Fleet, United States 
Navy. 

CIT. California Institute of Technology. 

COIR. A stiff elastic fiber made from the outer husk of the 
coconut. 

COMINCH. Commander in Chief, United States Navy. 

CONVERSION DESIGN. Design of an amphibian based on a 
conversion of an existing land vehicle or marine craft. 

CRIMP BARS. Flat bars crimped (or bent) to form subway- 
type floor sections. 

DEADLINE!). Non-operating. 

DEADMAN. Bulky article, such as a log, buried in the ground 
to serve as an improvised anchor. 

DECK SCUTTLE. A small opening in a deck, giving access to 
a compartment below deck. 

DOLOC. Demolition of Obstacles to Landing Operations Com¬ 
mittee, NDRC. 

DROGUE. A device generally made of canvas over a heavy 
framework, used for slowing down or steadying in the water 
the object to which it is attached. 

DRY FERRY. Ferrying with load completely out of water. 

DUKW. General Motors Corporation 2i/2-ton, 6x6 amphibian. 

EAC. Engineer Amphibian Command. 


c 


337 



338 


GLOSSARY 


EGG. Project for development of 10-ton missile for long-range 
airborne attack against enemy ships or clams. 

EMERGED TRACK PROPULSION. In a track-propelled am¬ 
phibian, track propulsion with the return track out of water. 

ESB. Engineer Special Brigade of United States Army. 

ETO. European Theater of Operations. 

F. Degrees Fahrenheit. 

FENDER. Bumper made of soft material, used to cushion the 
shock when a vessel strikes another object. 

FOOI ROPE. A rope along the lower edge of a sail or net. 

FOREFOOT. The sharp section of the bow at the water level. 

FORESTAY. Forward stay for a mast. 

FREEBOARD. The height of the hull remaining above the 
waterline. 

G-3. Plans and Training Division of a headquarters. 

G-4. Supply Division of a headquarters. 

CMC. General Motors Corporation. 

GRADE ABILITY*. Limiting angle of climb. 

GROUND-UP DESIGN. Design of an amphibian based on a 
completely new arrangement of components, not a conversion 
of any existing land vehicle or marine craft. 

GROUSER. In a track-propelled vehicle, a structure secured to 
the track to improve propulsion. 

GUEST WARP. A heavy rope hung over the side of the ship 
along the length of its hull to provide a means of mooring 
small craft. 

HEADROPE. A rope along the upper edge of a sail or net. 

HELL CAT. 76-mm gun motor carriage. 

HIGGINS BOAT. See LCYP. 

HOG TROUGH. A chute for discharging cargo by hand over 
the side of a DUKW. 

HOPPER. A mail who assists a DUKW’ driver at shipside in 
mooring and loading cargo into the DUKW. 

HQ. Headquarters. 

IDLER. In a track-propelled vehicle, a wheel which serves 
merely as a support for a track and does not transmit power 
to it. 

J. Jet reaction in pounds/displacement. 

JANET. Joint Army-Navy Experimental and Testing Board. 

JF.T REACTION. Reaction to the propulsive force of a jet. 

JCS. United States Joint Chiefs of Stall. 

JEEP. 14 -ton, 4x4 truck. 

KITE. Device used to hold torpedo net or similar underwater 
gear out from ship. 

LCM. Landing Craft, Mechanized. 

LCM(3). Landing Craft, Mechanized—Mark 3. 


LCT. Landing Craft, Tank. 

LCT(5). Landing Craft, Tank—Mark 5. 

LCT(6). Landing Craft, Tank—Mark 6. 

LCV. Landing Craft, Vehicle. 

LCVP. Landing Craft, Vehicle, Personnel (Higgins Boat). 
LEECH ROPE. A rope along the trailing edge of a sail or net. 
LOA. Over all length. 

LSD. Landing Ship, Dock. 

LSM. Landing Ship, Medium. 

LS I’. Landing Ship, Tank (United States built). 

LST(I). Landing Ship, Tank—Class 1 (British built). 

LSV. Landing Ship, Vehicle. 

L/T. Length of track on ground/tread. 

LUFF ROPE. A rope along the leading edge of a sail or net. 

LVT. Landing Vehicle, Track. 

LVT(l). Landing Vehicle, Track—Mark 1. 

I \'T(2). I anding Vehicle, Track—Mark 2. 

LVT(3). Landing Vehicle, Track—Mark 3 (Buffalo). 

LCV(4). Landing Vehicle, Track—Mark 4 (Amtrac). 

LVT(A). Landing Vehicle, Track (Armored). 

LVT(A)(1). Landing Vehicle, Track (Armored)—Mark 1 
(Amtank). 

LVT(A)(2). Landing Vehicle, Track (Armored)—Mark 2. 
LVT(A)(4). Landing Vehicle, Track (Armored)—Mark 4. 

IAVL. Waterline with vessel loaded. 

MTER. Motor transport engineering request (for change) 
(General Motors Corporation). 

MTO. Mediterranean Theater of Operations. 

NALOC. Navigational Aids to Landing Operations Committee, 
NDRC. 

NDRC. National Defense Research Committee. 

OA. Over all. 

OCOD. United States Army Oflice of Chief of Ordnance, De¬ 
troit, Michigan. 

OFS. Office of Field Service, OSRD. 

105. 105-mm howitzer. 

OSRD. Office of Scientific Research and Development. 

PELICAN. Amphibious cargo carrier with payload greater than 
2(4 tons. 

POA. Pacific Ocean Areas. 

PROPELLER PITCH RATIO. Ratio of diameter of the blade 
to pitch of the blade. 



GLOSSARY 


339 


l’ROTECTOSCOPE. In tanks, a built-in periscope-like device 
designed to permit indirect vision while protecting the ob¬ 
server from enemy gunfire. 

QUARTERING SEAS. Seas approaching at an angle of ap¬ 
proximately 45 degrees from the stern. 

RAKE FRAMING. Framing not square to the line of the keel, 
such as occurs at the bow and stern of most vessels. 

RASC. Royal Army Service Corps (British). 

RESERVE BUOYANCY. Amount of buoyancy remaining after 
loading. 

R/F PLATE. Reinforcing plate. 

RIPPLE FIRE. Fire given in rapid sequence. 

RITCHIE DEVICE. Auxiliary metal pontons for tank flotation. 

RUB RAIL. Rail along the outer side of the hull, installed to 
protect the hull sides themselves from damage in contact with 
other objects. 

SCORPION. Mobile rocket launcher. 

SCHUSS. Downhill run on skis. 

SCOUR HOLES. Holes cut in the face of a coral reef by action 
of the sea. 

SEABISCUIT. Project for development of methods to protect 
tanks against antitank mines. 

SEAC. Southeast Asia Command. 

SETTING SUN. Project for development of long-range, glider- 
borne, remote-controlled torpedoes. 

SHROLJD. The side stays of a mast. 

SKIRT HOLES. In a track-propelled amphibian, various sizes 
and arrangements of holes in the track skirt along the line of 
the rear track tunnel, above and below the track, and at sev¬ 
eral stations along the track. 

SNAKE. Project for development of jet-propelled amphibious 
demolition charge. 

SOPAC. South Pacific Command. 

SOVVESPAC. Southwest Pacific Command. 

SPRING LINES. Lines used in mooring a vessel, so rigged that 
those lines attached to the bow lead aft, and those attached to 
the stern lead forward. 


STEEP-TO BEACH. Beach shelving sharply into deep water. 

STERN CELL. Watertight compartment attached to the stern 
to increase buoyancy. 

STERN SCOOP. In a track-propelled amphibian, a device 
similar to a standard bowblock mounted around an idler at 
the stern end of the track. 

STERN STRIPPING. In a track-propelled amphibian, strip¬ 
ping of the water at the rear idler by means of a vertical plate 
tangent to the track as it passes around the idler. 

STERN WING. In a track-propelled amphibian, a device to 
strip water off the stern end of the return track and to turn it 
180 degrees outboard and astern. 

STRIPPER PLATE, In a track-propelled amphibian, a plate 
installed tangent to the track to strip the flow of return water. 

SUBMERGED TRACK PROPULSION. In a track-propelled 
amphibian, track propulsion with all tracks under water. 

SLIRF PLATE. A plate on the bow of a vessel to deflect spray. 

EC. United States Army Transportation Corps. 

T/E. Table of Equipment (United States Army). List which de¬ 
scribes the equipment officially authorized for an Army unit. 

END. Torpedo net defense. 

T/O. Table of Organization (United States Army). List which 
describes the personnel officially authorized for an Army unit. 

TRACK SKIRTS. In a track-propelled amphibian, extension 
of the hull outboard of the track, forming with the sponson 
and hull a tunnel in which the return track operates. 

TURTLE. Project for development of improved land combat 
vehicles; series of proposed improved land combat vehicles. 

VISION BLOCK. In tanks, a thick glass window constructed to 
give direct vision and at the same time provide maximum pro¬ 
tection against enemy fire. 

VISION CUPOLA. In tanks, a cupola designed to accommo¬ 
date one or more vision blocks, generally located over the 
head of the tank commander or driver. 

WDGS. United States War Department General Staff. 

WEASEL. Track-laying light cargo carrier. 

WET FERRY. Ferrying with load partly submerged. 

WL. Waterline. 

WT. Watertight. 



























BIBLIOGRAPHY* 


Chapter 1 
INTRODUCTION 

1. Bi-monthly Project Reports (Division 12 and Section 12.1) 
(Nos. 1-10), National Defense Research Committee, Febru¬ 
ary 19, 1943-December 1, 1914. Div. 12-0I00-M1 

Chapter 2 
AMPHIBIOUS JEEP 

1. Development and Tests of the 14 Ton 4x4 GPA Amphibian 

(QMC4) (Final report Sparkman & Stephens job No. 402), 
(n. a.), OEMsr-154, Sparkman & Stephens, Inc., New York, 
N. Y., July 4, 1944. Div. 12-0200-M23 

2. Operators Distraction Manual for Ford Amphibian x/^-ton 

4x4, (n. a.), Contract Number: W-398-QM-12 937 (W-372- 
ORD 2782), U.S.A. Reg. Numbers: 702104-709999 Inc., 
7010000-701213 Inc., 7012105-7014882 Inc., Ford Motor 
Company, Dearborn, Mich., [1942]. Div. 12-0200-M7 

3. Letter to P. C. Putnam, Subject: QMC-4 [General purpose 

amphibian truck] (Interim report No. 2), Roderick Ste¬ 
phens, Jr., Sparkman & Stephens, Inc., New York, N. Y., 
December 13, 1941. Div. 12-0200-M3 

4. Amphibian Scout Car , Design No. 402-6; Stevens model 

No. 397-2, (n. a.), Sparkman & Stephens, Inc., New York, 
N. Y., December 16, 1941. Div. 12-0200-M4 

5. QMC-4 [General purpose amphibian truck] (Interim re¬ 

port No. 3, December 5 to December 30, 1941), [Roderick 
Stephens, Jr.], Sparkman & Stephens, Inc., New York, N. Y., 
[December 30, 1941]. Div. 12-0200-M5 

6. Letter to P. C. Putnam. Subject: Continuance of QMC-4 

development by Marmon-Herrington Company [of the 
general purpose amphibian truck], Roderick Stephens, Jr., 
Sparkman & Stephens, Inc., New York, N. Y„ December 30, 
1911. Div. 12-0200-M6 

7. Amphibian Scout Car, Design No. 402-6; Stevens model 

No. 397-1, (n. a.), Sparkman & Stephens, Inc., New York, 
N. Y., November 22, 1941. Div. 12-0200-M2 

8 . QMC-4 [General purpose amphibian truck], Ford model 
No. L, Test program, (n. a.), January 26, 1942. 

Div. 12-0200-M8 

9. QMC-4 [General purpose amphibian truck] (Interim re¬ 
port No. 4 for January, 1942), Roderick Stephens, Jr., 
Sparkman 8: Stephens, Inc.. February 2, 1942. 

Div. 12-0200-M9 

10. Letter to Roderick Stephens, Jr. Subject: Self-propelled 
model of the amphibian scout car. Backing tests of Febru¬ 
ary 4, 1942, W. C. Hugh, Jr., Stephens Institute of Technol¬ 
ogy, Hoboken, N. J., February 5, 1942. Div. 12-0200-M10 

11. Self-propelled Tests on Amphibian Scout Car, Stevens 
Model No. 397 Test Data, (n. a.), Sparkman & Stephens, 
Inc., New York., N. Y., February 5, 1942. Div. 12-0200-M 11 


* Numbers such as Div. 12-0100-Ml indicate that the document 
listed has been microfilmed and that its title appears in the microfilm 
index printed in a separate volume. For access to the index volume and 
to the microfilm consult the Army or Navy agency listed on the reverse 
of the half-title page. 


12. QMC-4 Scale Model Testing [of the general purpose am¬ 

phibian truck] from September 23, 1941 to February 25, 
1942 (Supplementary report), Roderick Stephens, Jr., 
Sparkman 8: Stephens, Inc., New York, N. Y„ February 25, 
1942. Div. 12-0200-M12 

13. QMC-4. Full Scale Tests for No. 1 Pilot Model [General 

purpose amphibian truck] (General summary from Febru¬ 
ary 9, 1942 to February 21, 1942), Roderick Stephens, Jr., 
Sparkman & Stephens, Inc., New York, N. Y., February 26, 
1942. Div. 12-0200-M 13 

14. QMC-4 [General purpose amphibian truck] (Interim report 
No. 5 for February 1942), Roderick Stephens, Jr., Spark¬ 
man 8: Stephens, Inc., New York, N. Y., February 28, 1942. 

Div. 12-0200-M 14 

15. QMC-4 [General purpose amphibian truck] (Report No. 6 
for March, 1942), Roderick Stephens, Jr., Sparkman 8: 
Stephens, Inc., New York, N. Y., March 1942. 

Div. 12-0200-M15 

16. The 14 -ton 4x4 Amphibian Car T-l (Ford No. 1) (Interim 
report), Frederick J. Bogardus, War Department, The En¬ 
gineer Board, Fort Belvoir, Virginia, March 25, 1942. 

Div. 12-0200-M16 

17. Letter to Roderick Stephens, Jr. Subject: Brake and other 

tests, G. P. A. unit No. 2. Commencing April 18, 1942, 
James B. Murray, Sparkman Sc Stephens, Inc., New York, 
N. Y., May 1, 1942. Div. 12-0200-M 17 

18. QMC-4 [Full scale trials of general purpose amphibian 

truck] (Interim report No. 7 for April, 1942), Roderick 
Stephens, Jr., Sparkman 8: Stephens, Inc., New York, N. Y., 
May 14, 1942. Div. 12-0200-M18 

19. Specifications Amphibious Reconnaissance Car x/^-ton 4x4 

Model, (n. a.). Ford Motor Company, Dearborn, Mich., 
August 18, 1942. Div. 12-0200-M 19 

20. Amphibious Equipment and Vehicles Designed by Spark¬ 

man & Stephens, Die. for Period of May, 1941, to August, 
1942 (Preliminary summary report) (Alteration I: Roder¬ 
ick Stephens, Jr. Suggestions added 11-16-43), Lawrence G. 
Hecker, Sparkman Sc Stephens, Inc., New York, N. Y., 
[November 1943]. Div. 12-0200-M22 

21. Report on x/^-ton Amphibian Weapons Carrier Test Con¬ 
ducted at Camp Elliot, California, by the California Insti¬ 
tute of Technology, C. F. Kramer, Ford Motor Company, 
Dearborn, Mich., February 23, 1943. Div. 12-0200-M20 

22. The 1 4-ton 4x4 Amphibious Trucks (Intelligence sum¬ 
mary No. 169), (n. a.), TB-12-15-WD, War Department 
(Ordnance Intelligence Unit, Service Branch, Technical 
Division), Washington, D. C., April 16, 1943. 

Div. 12-0200-M21 

23. Model Tests to Investigate Smooth Water Speeds of Am¬ 
phibious Scout Car (QMC-4 Interim report No. 1, August 
8 to September 23), Roderick Stephens, Jr., Sparkman 8: 
Stephens, Inc., New York, N. Y., September 24, 1941. 

Div. 12-0200-M 1 

24. The 14 Ton 4x4 Amphibian, Built by Marmon Herrington 

for . . . Division 12, NDRC (Final report), Roger S. War¬ 
ner, Jr., OEMsr-182, Division 12, NDRC, September 26. 
1944.' Div. 12-0200-M24 




342 


BIBLIOGRAPHY 


25. Development and Tests of the 14 Ton 4x4 GPA Am- 12. 

phibian (QMC4) (Final report July 4, 1944, Sparkman &yf 
Stephens job No. 402; rewritten November 22, 1944 to in¬ 
corporate suggestions of Roderick Stephens, Jr.), [L. G. 
Hecker], Sparkman & Stephens, Inc., New York, N. Y., De¬ 
cember 30, 1944. Div. 12-0200-M25 13 - 

26. Amphibious Vehicle Design (Supplementary final report 
Sparkman & Stephens project No. 558, OEMsr-154), C. J. 
Nuttall, Jr. and L. G. Hecker, Sparkman & Stephens, Inc., 

New York, N. Y., March 30, 1945. Div. 12-0200-M26 

Chapter 3 '• 

THE DUKYV: ITS DEVELOPMENT 

1. General Motors Truck and Coach Amphibian, Model 
DUKW-353, Characteristics and Photographs, (n. a.), GMC 
Truck & Coach Division, General Motors Corporation, 
Pontiac, Mich., and Sparkman & Stephens, Inc., New York, 

N. Y„ June 12, 1942. Div. 12-0300-MI 

2. Model DU All’ -35 3 6x6 Amphibious Truck. Tentative sped- „ 

fication. April 27, 1942, E. W. Allen, GMC Truck & Coach 
Division, General Motors Corporation, Pontiac, Mich., Re¬ 
vised: August 8, 1942. Div. 12-0300-M3 

3. Model DUKW-353, (n. a), GMC Truck & Coach Division, 

General Motors Corporation, Pontiac, Mich., October 10, 

1942. Div. 12-0300-M4 

4. Truck Track, DUKW Spreading Equipment (Series No. 

7; Drawing 119-A), O. F. Arthur, Tri-State Engineering 
Company, Washington, Pa., May 1943. Div. 12-0300-M7 

5. The 21/2 Ton Amphibian Truck and Trailer, H. Rowe, OD- 
92, GMC Truck & Coach Division, General Motors Cor- 
poration, Pontiac, Mich., February 16, 1943. 

Div. 12-0300-M6 

6. Tire Tests on Coral Rock GMC Truck-Amphibian, Model 

DUKW-353 (Problem No. 59), H. W. Del/ell, The B. F. 
Goodrich Company, Akron, Ohio, [February, 1943]. '• 

Div. 12-0300-M5 

7. Ship to Shore Airplane Ferry Employing Catamaran Con¬ 
sisting of Two (2) DUKW-353 and Catamaran Kit, (n. a), 

GMC Truck & Coach Division, General Motors Corpora- 8. 
tion, Pontiac, Mich., November 22, 1943. Div. 12-0300-M8 

8 . Amphibious Equipment and Vehicles Designed by Spark- 
man & Stephens, Inc. ... for Period of May, 1941, to August, 

1943 (Preliminary summary report) (Alteration I: Roder- 9. 
ick Stephens, Jr. Suggestions added 11-16-43), Lawrence G. 
Hecker, Sparkman &: Stephens, Inc., New York, N. Y., 
[November, 1943]. Div. 12-0200-M20 

9. The 2 1/2 Ton Amphibian-DUKW (Interim reports Nos. 

4-13, 16, 20-21, 24-25), Roderick Stephens, Jr., Sparkman Sk 
Stephens, Inc.. New York, N. Y., July, 1942-April, 1944. 

Div. 12-0300-M2 1L 

10. Army 2\/ 2 Ton Amphibian Truck 6x6, GMC DUKW-353 

(Final report), Roderick Stephens, Jr., OEMsr-154, Spark¬ 
man & Stephens, Inc., New York, N. Y., November 7, 1944. 12. 

Div. 12-0300-M10 

11. Development of the DUKW and Related Projects; 2\/> Ton 

6x6 Amphibious Truck (Final report), C. O. Ball, OEMsr- 13. 
870, GMC Truck & Coach Division, General Motors Cor¬ 
poration, Detroit, Mich., [1944], Div. 12-0300-M9 


Amphibious Vehicle Design (Supplementary final report 
Sparkman & Stephens project No. 558, OEMsr-154), C. J. 
Nuttall, Jr. and L. G. Hecker, Sparkman & Stephens, Inc., 
New York, N. Y„ March 30, 1945. Div. 12-0200 \126 

The Truck Becomes a DUKW, (n. a.). General Motors Cor¬ 
poration, Detroit, Mich., [October, 1945]. Div. 12-0300-M11 

Chapter 4 

THE DUKW: ITS APPLICATIONS 

Truck, Amphibian, 2\/ 2 -ton, 6x6, GMC DUKW-353 (Tech¬ 
nical manual No. 9-802), (n. a.), War Department, Wash¬ 
ington, D. C. (Prepared by Chief of Ordnance and Yellow 
Truck and Coach Manufacturing Company), October 15, 

1942. 

DUKW, Amphibious Operation. Hints for You, the Driver, 
(n. a.), GMC Truck & Coach Division, General Motors 
Corporation, Pontiac, Mich., [November, 1942]. 

Div. 12-0400-MI 

Service Parts Catalogue for Truck, Amphibian DUKW- 
353 (Part II, SNL G-501); serial number 006 through 
2005), (n. a.), W-2425-QM-234, GMC Truck & Coach 
Division, General Motors Corporation, Pontiac, Mich., No¬ 
vember 1, 1942. 

Preventive Maintenance for DUKW, Model 353, (n. a.), 
GMC Truck & Coach Division, General Motors Corpora¬ 
tion, Pontiac, Mich., [December, 1942]. Div. 12-0400-M2 

DUKW Amphibious Operation (Second edition), (n. a.), 
GMC Truck & Coach Division, General Motors Corpora¬ 
tion, Pontiac, Mich., [May, 1943]. Div. 12-0400-M3 

Operation and Maintenance Instruction Course, DUKW 
353 Amphibious Truck, (n. a.), GMC Truck & Coach Divi¬ 
sion, General Motors Corporation, Pontiac, Mich., June 
1913. Div. 12-0400-M3 

Operations and Maintenance Course, DUKW-353 Am¬ 
phibious Truck (Instructor’s guide), (n. a.), GMC Truck & 
Coach Division, General Motors Corporation, Pontiac,' 
Mich., June, 1913. 

Sendee Parts Catalog for Truck, Amphibian DUKW-353 
(SNL G-501), (n. a.), W-374-ORD-2849, W-374-ORD-6523, 
(W-2425-QM-234), GMC Truck & Coach Division, General 
Motors Corporation, Pontiac, Mich., June 1, 1943. 

DUKW Troubles and Suggested Cures, Roderick Stephens, 
Jr., Sparkman & Stephens, Inc., New York, N. Y., July 9, 

1943. Div. 12-0400-M4 

DUKWs. Report on Trip to United Kingdom, May 9 to 
July 1 , 1943, Roderick Stephens, Jr., Sparkman &: Stephens, 
Inc., New York, N. Y„ July 12, 1943. Div. 12-0400-M5 

Amphibian Truck Company (Transportation corps, FM 
55-150). (n. a.), War Department, Washington, D. C., Octo¬ 
ber 1913. 

The 2i/> Ton Amphibian Trucks. Report on DUKWs, 
Captain Frank Speir, [War Department], Washington, 
D.C., October 1943. Div. 12-0400-M6 

Report on DUKW-Buffalo Tests, Conducted by U. S. Navy, 
Roderick Stephens, Jr., Sparkman & Stephens, Inc., New 
York, N. Y„ October 5, 1943. Div. 12-0400-M7 



BIBLIOGRAPHY 


343 


14. 


15. 


16. 


17. 


18. 


19. 


20 . 


21 . 


23. 


.'24. 


25. 


26. 


28. 


Care of DUKWs on Shipboard during Combat Shipment — 
Weight without Payload 1-1,500#, Roderick Stephens, Jr., 
Sparkman &: Stephens, Inc., New York, N. Y., October 25, 
1943. Div. 12-0400-M8 

\DUKW\; Operational Hints, Roderick Stephens, Jr., 
Sparkman &: Stephens, Inc., New York, N. Y., October 25, 
1943. Div. 12-0400-M9 

DUKWs in New Guinea, Palmer C. Putnam, November 9, 
1943. Div. 12-0400-M12 

DUKW Mooring at Ship’s Side (October 25, 1943), Rod¬ 
erick Stephens, Jr., Sparkman & Stephens, Inc., New York, 
N. Y., Revised: November 17, 1943. Div. 12-0400-M13 

Care of DUKWs on Shipboard during Combat Shipment — 
Weight without Payload 14,500# (October 25, 1943), Re¬ 
vised: Roderick Stephens, Jr., Sparkman & Stephens, Inc., 
New York, N. Y., November 17, 1943. Div. 12-0400-M14 

. . . Landing Problems Using LSTs, DUKWs, Buffaloes, and 
Alligators. Report of Observations by D. Puleston . . . of 
[tests] Carried Out near Puni Puni on November 16 and 
17, 1943 . . ., Palmer C. Putnam, November 21, 1943. 

Div. 12-0400-M15 

Recommendations Relating to DUKWs, Palmer C. Putnam, 
November 22, 1943. Div. 12-0400-M16 

[DUKW]; Obseiuations and Suggestions Based on . . . Visit 
to A.V.T.C., Charleston, South Carolina, October 28, 1943, 
Roderick Stephens, Jr., Sparkman &: Stephens, Inc., New 
York, N. Y„ [November, 1943(?)]. Div. 12-0400-M10 


29. Initial Supply of 7th Infantry Division Units by DUKWs 
during Assault Phases of Landings on Leyte, P. I. 
(USAFFE board report No. 226, November 21, 1944), M. B. 
Kendrick, War Department (United States Army Forces in 
the Far East), Washington, D. C., March 31, 1945. 

30. DUKW Lighterage Operations—Lingayen Gulf (USAFFE 
board report No. 233, February 24, 1945), M. B. Kendrick, 
War Department (United States Army Forces in the Far 
East), Washington, D. C., March 31, 1945. 

31. DUKW Lighterage Operations — Leyte (USAFFE board 
report No. 243, December 19, 1944), M. B. Kendrick, War 
Department (United States Army Forces in the Far East), 
Washington, D. C., April 6, 1945. 

32. The DUKW; Its Operation and Uses (Revised edition of 
October 15, 1944), Colonel O. N. Thompson, War Depart¬ 
ment (Headquarters United States Army Forces, Pacific 
Ocean Areas), Washington, D. C., May 15, 1945. 

Div. 12-0400-M20 

33. DUKW Operations. Survey at Okinawa as of July 5, 1945, 

Dennis Puleston, Office of Scientific Research and Develop¬ 
ment, [1945]. Div. 12-0400-M18 

34. The 2I/O Ton, 6x6, DUKW-353, Amphibian; MTER Rec¬ 

ord of Production Changes (Revised), (n. a.), GMC Truck 
& Coach Division, General Motors Corporation, Pontiac, 
Mich., August 23, 1945. Div. 12-0400-M21 


Chapter 5 


Inspection, Maintenance, and Care of the Lorry 2\/ 2 -ton 
6x6 GS (amphibious) (GMC DUKW 353) (Provisional), 1 he 
War Office (Chief of the Imperial General Staff), London, 
England, December 1943. 

Emergency Field Maintenance for 2i/ 2 -ton Amphibian 
Truck (Technical bulletin Old. 5), War Department, 
Washington, D. C., December 31, 1943. 


Amphibious Equipment and Vehicles Designed by Spark¬ 
man & Stephens, Inc.. .. for Period of May, 1941, to August, 
1943 (Preliminary summary report) (Alteration I: Rod¬ 
erick Stephens, Jr. Suggestions added 11-16-43), Lawrence 
G. Hecker, Sparkman & Stephens, Inc., New York, N. Y., 
[November, 1943]. Div. 12-0200-M20 


/ 


THE WEASEL 
General 

The Weasel; Snow, Mud, and Deep Water Operations. U. 
S. M-29, (n. a.), Studebaker Corporation, South Bend, Ind., 
[January, 1944]. Div. 12-0500-MI 

Track Propelled Amphibians and Conversions That Spark¬ 
man & Stephens, Inc. Has Assisted in Developing, and. The 
Use of Completely Submerged Tracks for Propulsion in the 
Water (Summary report), Lawrence G. Hecker & Cliiford 
J. Nuttall, Jr., Sparkman & Stephens, Inc. project No. 500, 
Sparkman & Stephens, Inc., New York, N. Y., May 31, 1944. 

Div. 12-0500-M2 


The DUKW; Its Operation and Uses (Manual), (n. a.), 
War Department (Headquarters United States Army 
Forces, Pacific Ocean Area), Washington, D. C., October 15, 
19 44 . Div. 12-0400-M17 

The 2\/ 2 Ton Amphibious Truck (Interim reports Nos. 
14-15, 17-19, 21, 24, 29). Roderick Stephens, Jr., Sparkman 
& Stephens, Inc., New York, N. Y., October 19, 1943-No- 
vember 14, 1944. Div. 12-0400-MI 1 


3. Weasel Snow Vehicle (Final report Sparkman & Stephens 
job No. 437), (n. a.), OEMsr-154, Sparkman & Stephens, 
Inc., New York, N. Y., July 17, 1944. Div. 12-0500-M3 

4. The Weasel (A paper to be presented March 19, 1945 be¬ 
fore the Society of Automotive Engineers), H. E. Churchill, 
Studebaker Corporation, South Bend, Inch, March 19, 1945). 

Div. 12-0500-M1 


Cargo Handling - Marshall Islands Operation (OPDIB 
amphibious supplement No. 2), War Department (Opera¬ 
tions Division War Department General Stall), Washing¬ 
ton, D. C., March 10, 1945. 

The DUKW'; Its Operation and Uses, with Changes and 
Additions (Extracts), Colby M. Myers, War Department 
(Headquarters 4th Engineer Special Brigade), Washing¬ 
ton, 1). C., March 26, 1945. Div. 12-0400-M19 


The T-15 Weasel 

5. Photograph, Subject: Motors for snow and ice: the auto¬ 
mobile adapted to the sleigh, London Illustrated News, 
London, Eng., 1908; Vol. 132, p. 160. Div. 12-0510-MI 

6 . Photograph, Subject: A Novel Motor Sleigh [invented by 

Remizi], The Horseless Age, New York, N. Y., February 24, 
1912. Div. 12-0510-M2 


A1 





BIBLIOGRAPHY 


•544 


/. 


8 . 

9. 




12 . 


13. 


14 . 


15 . 


16. 


17 . 


18. 


19. 


20 . 


21. 


Photograph, Subject: Motoring in a new style. Standard 
snow motor to be manufactured in Seattle. Revolving 
drums with spirals furnish propelling force. Illustrated 
Motor Age, March 18, 1920. Div. 12-0510-M3 

Photograph, Subject: Radantrieb, Der Motorwagen, Ber¬ 
lin, Germany, December 20, 1921, p. 205. Div. 12-0510-M4 


23. The T-15 Cargo Carrier; Progress Report on the Tentative 
Program for Further Development, (n. a.), Studebaker Cor¬ 
poration, South Bend, Ind., April 22, 1943. Div. 12-0520-M3 

24. The Light Cargo Carrier U. S. T-24; General Information, 

(n. a.), Studebaker Corporation, South Bend, Ind., May 20, 
1943. Div. 12-0520-M4 


Super Snow Bird Traveling Equipment (New 1940 model 
for model A & V 8 standard Ford cars), (n. a.), Arps Corpo¬ 
ration, New Holstein, Wis., [1940], 

The Snow Characteristics of Aircraft Skis (Report MM-57), 
G. J. Klein, National Research Council of Canada, Ottawa, 
Canada, February 26, 1942. 

Motor Vehicles for Travel on Snow (Report No. MM-58), 
G. J. Klein, National Research Council of Canada, Ottawa, 
Canada, July 6 , 1942. 

Eliason Motor Toboggan, (n. a.), The Four Wheel Drive 
Auto Co., Clintonville, Wis., Kitchener, Ontario, Canada, 
(n. d.). 

Development of Weasel, with Notes on Problems of Its Use, 
Palmer C. Putnam, NDRC, Section C-2, October 14, 1942. 

Div. 12-0510-M6 


25. The Light Cargo Carrier, T-24, (n. a.), War Department 
technical manual No. 9-772, War Department, Washing¬ 
ton, D. C„ June 19, 1943. 

26. Handbook of Instructions for the Use and Maintenance of 
Cluster Parachutes — Used in a Cluster Assembly of Four 
Parachutes for Aerial Delivery of U. S. T-15 and/or T-24 
Light Cargo Carriers, U. S. Army, July 1, 1943. 

27. Engine, Engine Accessories, and Clutch for Light Cargo 
Carrier, T-24, (n. a.), War Department technical manual 
No. 9-1772A, War Department, Washington, D. C., July 2, 
1943. 

28. The Light Cargo Carrier; Development and Redesign, 

(n. a.), OEMsr-635, Studebaker Corporation, South Bend, 
Ind., January 17, 1944. Div. 12-0520-M5 


Development of Weasel, with Notes on Problems of Its 
Use (Interim report), Palmer C. Putnam, NDRC, Section 
C-2, November 2, 1942. Div. 12-0510-M7 

Brief Chronological History of the Development Program 
of T-15 between May 17, 1942 and November 2, 1942, 
Volumes I, II, and III, (n. a.), Studebaker Corporation, 
South Bend, Ind., [November 2, 1942]. Div. 12-0510-M8 

Summary of T-15 Tests Made at Studebaker Proving 
Ground and the Columbia Ice Fields, (n. a.), Studebaker 
Corporation, South Bend, Ind., November 20, 1942. 

Div. 12-0510-M10 


The M-29C Weasel (Ark) 

29. The M-29 Cargo Carrier LT, Modified Amphibian, Tested 
by XIX Corps, Camp Polk, La., November 16, 1943 to De¬ 
cember 10, 1943, Kelvin O'Shea, December 10, 1943. 

30. The M-29 Cargo Carrier; Development and Tests of Modi¬ 

fication Equipment for Improved Deep-Water Propulsion, 
H. E. Churchill, OEMsr-1166, Studebaker Corporation, 
South Bend, Inch, April 10, 1944. Div. 12-0530-MI 

31. Cargo Carrier M-29-C, (n. a.), U. S. Army, Ordnance De¬ 
partment, Technical Division, April 1944. 


Cargo Carrier, Light T-15. General Specifications, Dimen¬ 
sional Layout, Outline Draining, (n. a.), Studebaker Corpo¬ 
ration, South Bend, Ind., [November 4, 1942]. 

Div. 12-0510-M9 



Photographs, Cargo Carrier, Light T-15, Albums A and B, 

(n. a.), Studebaker Corporation, South Bend, Ind., [1942]. 33 . 

Div. 12-0510-M5 


Light Cargo Carrier, T-15, War Department technical man¬ 
ual No. 9-893, (n. a.), War Department, Washington, D. C., 
February 5, 1943. y* 4 ’ 


Letter to P. C. Putnam, Subject: Flynn’s Snow Motor 
(Blueprint of snow tractor attached), Roy E. Cole, Stude¬ 
baker Corporation, South Bend, Ind., April 16, 1945. 

Div. 12-0510-MI 1 


Ark Amphibious Conversion of Weasel, The M-29 Light 
Cargo Carrier (Final report; Sparkman & Stephens job 
No. 462), (n. a.), OEMsr-154, Sparkman & Stephens, Inc., 
New York, N. Y., July 17, 1944. Div. 12-0530-M2 

The Cargo Carrier, M-29-C; Its Operation and Uses, (n. a.). 
War Department (Headquarters United States Army 
Forces, Pacific Ocean Areas), January 20, 1945. 

Amphibious Vehicle Design (Supplementary final report 
Sparkman & Stephens project No. 558, OEMsr-154), C. J. 
Nuttall, Jr. and L. G. Hecker, Sparkman & Stephens, Inc., 
New York, N. Y., March 30, 1945. Div. 12-0200-M26 

Tactical Use 


The M-29 (T-24) Weasel 

The T-15 Cargo Carrier; Tentative Program for Further 
Development, (n. a.), Studebaker Corporation, South Bend, 
Ind., December 23, 1942. Div. 12-0520-MI 

The T-15 Cargo Carrier; Progress Report on the Develop¬ 
ment, (n. a.), Studebaker Corporation, South Bend, Ind., 
March 29, 1943. Div. 12-0520-M2 


35. Test of Light Cargo Carrier, M-29-C, SNL G-179, 24 March 
1944 to 8 April 1944, (n. a.). War Department (7th In¬ 
fantry Division, APO 7, c/o Postmaster, San Francisco, 
California), April 1944. 

36. Reports of British Assault Training and Development Cen¬ 
ter, Monthly Progress Reports, September 13, 1944, John 
A. Hornbeck, NDRC, Land Mines Committee, November 
1944. 


CO.' 



BIBLIOGRAPHY 


Chapter 6 

AMPHIBIOUS GUN MOTOR CARRIAGE 


Chapter 8 

PROPOSED AMPHIBIOUS VEHICLES 


345 


1. Track Propelled Amphibians and Conversions That Spark¬ 
man cir Stephens, Inc., Has Assisted in Developing, and. 
The Use of Completely Submerged Tracks for Propulsion 
in the Water (Summary report), Lawrence G. Hecker and 
Clifford J. Nuttall, Jr., Sparkman & Stephens project No. 
500, Sparkman &: Stephens, Inc., New York, N. Y., May 31, 
1944. Div. 12-0500-M2 

2- Esch Device; [an] Amphibian Based on 76-mm Gun Motor 
Carriage M-1S, L. G. Hecker, Sparkman & Stephens job 
No. 484, Sparkman & Stephens, Inc., New York, N. Y., 
June 25, 1944. Div. 12-0600-MI 


1. Amphibious Equipment and Vehicles Designed by Spark¬ 

man ir Stephens, Inc. . . for Period of May, 1941, to August, 
1943 (Preliminary summary report), (Alteration I: Rod¬ 
erick Stephens, Jr. Suggestions added 11-16-43), Lawrence 
G. Hecker, Sparkman & Stephens, Inc., New York, N. Y., 
[November, 1943.] Div. 12-0200-M20 

2. Pelican Studies; [the] 6 Ton (6x6) Amphibians (Final re¬ 

port; Sparkman & Stephens job No. 435), (n. a.), OEMsr- 
154, Sparkman & Stephens, Inc., New York, N. Y., July 3, 
1944. Div. 12-0800-MI 


3. Report on Tests and Modifications on the Amphibious 
76-mm Gun Motor Carriage T-86 in the Period August 10, 
1944 to September 1, 1944 at the Aberdeen Proving 
Grounds, Maryland, and Rehobeth Beach, Delaware, C. J. 
Nuttall, Jr., Sparkman & Stephens job No. 484, Sparkman 
& Stephens, Inc., New York, N. Y., September 8, 1944. 

Div. 12-0600-M2 

Amphibious 76-mm Gun Motor Carriage T-86; Report of 
Landing Vehicle Board Trials at Fort Ord, California, 
L. G. Hecker, Sparkman & Stephens, Inc., New York, N. Y., 
October 11, 1944. Div. 12-0600-M3 

5. Amphibian Based on 76-mm Gun Motor Carriage M-18 
(Final report; Sparkman & Stephens job No. 484), L. |. 
Hecker, Sparkman & Stephens, Inc., New York, N. Y., 
December 30, 1944. Div. 12-0600-M4 

jk Amphibious Vehicle Design (Supplementary final report 
Sparkman & Stephens project No. 558, OEMsr-154), C. 
Nuttall, Jr. and L. G. Hecker, Sparkman & Stephens, In 
New York, N. Y., March 30, 1945. Div. 12-0200-M26 


3. Amphibious Trailers (Final report; Sparkman & Stephens 

job No. 439), (n. a.), OEMsr-154, Sparkman & Stephens, 
Inc., New York, N. Y„ July 5, 1944. Div. 12-0800-M2 

4. Tractor Trailer Atnphibians (Final report; Sparkman & 
Stephens job No. 449), (n. a.), OEMsr-154, Sparkman & 
Stephens, Inc., New York, N. Y., July 5, 1944. 

Div. 12-0800-M3 

5. Half Track and Special Feature Amphibians; Pelican Stud¬ 

ies Continued (Final report; Sparkman &: Stephens job 
No. 450), (n. a.), OEMsr-154, Sparkman & Stephens, Inc., 
New York, N. Y„ July 11, 1944. Div. 12-0800-M4 

The 15 Ton, J4 Track, Amphibious Cargo Carrier (Final 
report; Sparkman & Stephens job No. 513), [L. G. Hecker], 
[OEMsr-154], Sparkman & Stephens, Inc., New York, N. Y., 
[December 30, 1944], Div. 12-0800-M5 

7. Amphibious Vehicle Design (Supplementary final report; 
Sparkman & Stephens project No. 558), OEMsr-154, C. J. 
Nuttall, Jr. and L. G. Hecker, Sparkman & Stephens, Inc., 
New York, N. Y., March 30, 1945. Div. 12-0200-M26 



Chapter 7 
PADDY VEHICLE 

1. Amphibious Equipment and Vehicles Designed by Spark¬ 

man & Stephens, Inc. . . for Period of May, 1941, to August, 
1943 (Preliminary summary report) (Alteration I: Rod¬ 
erick Stephens, Jr. Suggestions added 11-16-43), Lawrence 
G. Hecker, Sparkman & Stephens, Inc., New York, N. Y., 
[November 1943]. Div. 12-0200-M20 

2. “Paddy Vehicle”; [an] Amphibious Cargo Carrier Based on 

T-39 Light Tractor (Final report; Sparkman & Stephens 
job No. 533), [L. G. Hecker], OEMsr-154, Sparkman & 
Stephens, Inc., New York, N. Y., [December 30, 1944]. / 

Div. 12-0700-M1 

Track Propelled Amphibians and Conversions That Spark¬ 
man & Stephens, Inc. Has Assisted in Developing, and. The 
Use of Completely Submerged Tracks for Propulsion in 
the Water (Summary report), Lawrence G. Hecker & 
Clifford J. Nuttall, Jr., Sparkman & Stephens project No. 
500, Sparkman & Stephens, Inc., New York, N. Y., May 31, 
1944. Div. 12-0500-M2 


Chapter 9 

AMPHIBIOUS DEVICES 

Amphibious Equipment and Vehicles Designed by Spark¬ 
man 6- Stephens, Inc. . . for Period of May, 1941, to August, 
1943 (Preliminary summary report) (Alteration I: Rod¬ 
erick Stephens, Jr. Suggestions added 11-16-43), Lawrence 
G. Hecker, Sparkman & Stephens, Inc., New York, N. Y., 
[November, 1943], Div. 12-0200-M20 

Track Propelled Amphibians and Conversions That Spark¬ 
man & Stephens, Inc. Has Assisted i?i Developing, and, The 
Use of Completely Submerged Tracks for Propulsions in 
the Water (Summary report), Lawrence G. Hecker & 
Clifford J. Nuttall, Jr., Sparkman & Stephens, Inc. project 
No. 500, Sparkman & Stephens, Inc., New York, N. Y., May 
31, 1944. Div. 12-0500-M2 

3. Light Tank Flotation (Final report; Sparkman & Ste¬ 
phens job No. 443), (n. a.), OEMsr-154, Sparkman & Ste¬ 
phens, Inc., New York, N. Y., July 3, 1944. Div. 12-0900-MI 


Amphibious Vehicle Design (Supplementary final report 
Sparkman & Stephens project No. 558, OEMsr-154), C. J. 
Nuttall, Jr. and L. G. Hecker, Sparkman & Stephens, Inc., 
New York, N. Y„ March 30, 1945. Div. 12-0200-M26 


4. Pontons for Vehicle Flotation (Final report; Sparkman 
& Stephens job No. 479), (n. a.), OEMsr-154, Sparkman & 
Stephens, Inc., New York, N. Y., July 4, 1944. 

Div. 12-0900-M2 








346 


BIBLIOGRAPHY 


“Ritchie Project” [Devices]; Tank Flotation (Final re¬ 
port; Sparkman & Stephens job No. 497), [L. G. Hecker], 
OEMsr-154, Sparkman Ik- Stephens, Inc., New York, N. Y., 
[December 30, 1944]. Div. 12-0900-M3 



. Amphibious Vehicle Design (Supplementary final report 
Sparkman Sc Stephens project No. 558), OEMsr-154, C. J. 
Nuttall, Jr. and L. G. Hecker, Sparkman & Stephens, Inc., 
New York, N. Y„ March 30. 1945. Div. 12-0200-M26 


7. Special Trailer Hitch (Final report; Sparkman & Ste¬ 
phens Inc. job No. 579), Olin J. Stephens II, OEMsr-154, 
Sparkman & Stephens, Inc., New York, N. Y., June 28, 1945. 

Div. 12-0900-M4 


8 . Project: “Snake” (Final report; Sparkman & Stephens job 
No. 594), Olin J. Stephens II, OEMsr-154, Sparkman & 
Stephens, Inc., New York, N. Y., June 28, 1945. 

Div. 12-0900-M5 


Chapter 10 

AMPHIBIOUS STUDIES 


Track Propelled Amphibians and Conversions That Spark¬ 
man &r Stephens, Inc. Has Assisted in Developing, and, The 
Use of Completely Submerged Tracks for Propulsion in the 
Water (Summary report), Lawrence G. Hecker & Clifford 
J. Nuttall, Jr., Sparkman & Stephens project No. 500, Spark¬ 
man & Stephens, Inc., New York, N. Y., May 31, 1941. 

Div. 12-0500-M2 


J&. Comparison of Emerged and Submerged Tracks for Water 
Propulsion (Final report; Sparkman & Stephens job No. 
536), [L. G. Hecker], OEMsr-154, Sparkman & Stephens, 
Inc., New York, N. Y., [December 30, 1944]. 

Div. 12-1000-MI 


3. Letter to P. C. Putnam, Subject: Proposed booster pro¬ 

pelled landing boat (File job No. 5721), Olin J. Stephens II. 
Sparkman & Stephens, Inc., New York, N. Y., January 2, 
1945. Div. 12-1000-M2 

4. Amphibious Vehicle Design (Supplementary final report 
/■ Sparkman & Stephens project No. 558), OEMsr-154, C. J. 

Nuttall, Jr., and L. G. Hecker, Sparkman Sc Stephens, Inc., 
New York, N. Y„ March 30, 1945. Div. 12-0200-M20 


5. Proposed Booster Propelled Landing Boat (Final report; 
Sparkman & Stephens job No. 572), Olin J. Stephens II, 
OEMsr-154, Sparkman & Stephens, Inc., New York, N. Y., 
June 28, 1945. Div. 12-1000-M3 


Chapter 11 

PONTON BRIDGE REACTIONS 

1. Reactions of Ponton Bridges with and without Articula¬ 
tion, H. L. Bowman, OEMsr-41, Drexel Institute of Tech¬ 
nology, Philadelphia, Pa., June 15, 1945. Div. 12-1100-MI 

Chapter 12 

BRIDGE, PONTON, AND FERRY DESIGNS 

1. The 200-ft. Portable Bridge [design prepared by Carson 8c 
Carson], H. L. Bowman, Drexel Institute of Technology, 
Philadelphia, Pa., [March 19, 1941]. Div. 12-1200-MI 


2. The Inglis Bridge, H. L. Bowman, Drexel Institute of 
Technology, Philadelphia, Pa., March 31, 1941. 

Div. 12-1200-M2 

3. Temporary Highway Trestles, Hartley Rowe, NDRC, Sec¬ 
tion C-2, April 16, 1941. Div. 12-1200-M3 

4. General Description of Floating Equipment for Carrying 
Tanks across Water (Sparkman & Stephens job No. 401), 
(n. a.), Sparkman & Stephens, Inc., New York, N. Y., May 

19.1941. Div. 12-1200-M5 

5. Ponton Bridges and Ferries for 30 Ton Tanks, Harry 
Balke, American Bridge Company, Pittsburgh, Pa., May 

29.1941. " Div. 12-1200-M6 

6 . The 90-ton Pontoon-Ferry (Design consideration and en¬ 
gineering preliminaries), T. Rees Tarn, Pittsburgh, Pa., 

May 1941. Div. 12-1200-M4 

7. Heavy Ponton Ferry; Design No. 2 (Second report on 

engineering determination), T. Rees Tarn, Pittsburgh, Pa., 
June 1941. Div. 12-1200-M7 

8 . [Available Materials, Loads, Stresses, and Clearances in 
Connection with the Design of Portable Bridges and Over¬ 
passes], William F. Carson, NDCrc-41. Carson & Carson, 
Philadelphia, Pa., September 22, 1941. Div. 12-1200-M8 

9. Letter to Captain F. S. Besson, Jr., Subject: Portable bridges 

designed by Bethlehem Steel Company, H. L. Bowman, 
File 653 (SP341), Drexel Institute of Technology, Phila¬ 
delphia, Pa., December 19, 1941. Div. 12-1200-M9 

10. Letter to Lieutenant Colonel W. C. Baker, Jr., Subject: 

Possible use as a railway bridge for the H-20 highway 
bridge, H. L. Bowman, Drexel Institute of Technology, 
Philadelphia., Pa., May 11, 1942. Div. 12-1200-M 10 

11. Trestle and Ponton Bridge for 60-ton Tanks [design pre¬ 
pared by Carson & Carson], H. L. Bowman, Drexel Insti¬ 
tute of Technology, Philadelphia, Pa., June 30, 1942. 

Div. 12-1200-M11 

12. Tube Bridge, H. L. Bowman, Drexel Institute of Tech¬ 
nology, Philadelphia, Pa., July 28, 1912. Div. 12-1200-MI2 

13. [Trestle for 60-ton Tanks; Railroad Loads Calculations; 

Pipe Structure; Landing Pier; and Knock-down Truss], 
William F. Carson, OEMsr-216, Carson & Carson, Phila¬ 
delphia, Pa., December 31, 1942. Div. 12-1200-M13 

14. Design of Solid-floor Treadway Bridge [design prepared by 
Carson & Carson], H. L. Bowman, OEMsr-216, Drexel In¬ 
stitute of Technology, Philadelphia, Pa., April 19, 1943. 

Div. 12-1200-M14 

15. Landing Pier [design prepared by Carson & Carson], H. L. 

Bowman, OEMsr-216, Drexel Institute of Technology, 
Philadelphia, Pa., April 27, 1943. Div. 12-1200-M 15 

16. Quay Repairs, H. L. Bowman, OEMsr-41, OEMsr-216, 

Drexel Institute of Technology, Philadelphia, Pa., June 
24, 1943. Div. 12-1200-M 16 

17. Tank Ferrying Barge and Transport Vessel (Sparkman 

& Stephens design No. 401, completed May, 1941), Lawrence 
G. Hecker, Sparkman & Stephens, Inc., New York, N. Y., 
July 20, 1943. Div. 12-1200-M17 

18. Articulated Bridge for 20-ton Loads, H. L. Bowman, Drexel 

Institute of Technology, Philadelphia, Pa., October 22, 
1943. Div. 12-1200-M18 


G QNi;ia WTnrU 



BIBLIOGRAPHY 


347 


19. [Ponton Bridge Using 2i/>-ton Amphibious Trucks; Fifteen 
Foot Treadway with Wood Floor; Quay Repairs; Articu¬ 
lated Bridge 20 Ton Capacity on Tube Float, and Alu¬ 
minum Alloys ], William F. Carson, NDCrc-41, OEMsr-216, 
Carson & Carson, Philadelphia, Pa., December 31, 1943. 

Div. 12-1200-M19 

20. Ramp for Solid-floor Treadway Bridge [design prepared 

by Carson & Carson], H. L. Bowman, OEMsr-41, OEMsr- 
216, Drexel Institute ol Technology, Philadelphia, Pa., 
January 31, 1944. Div. 12-1200-M20 

21. Ramp for Sparkman & Stephens “Army" Bridge, H. L. 

Bowman, OEMsr-41, Drexel Institute of Technology, Phil¬ 
adelphia, Pa.. June 19, 1944. Div. 12-1200-M21 

Chapter 13 

TESTS OF BRIDGE COMPONENTS 

Tests of Douglas Fir Balk 

1. Tests on Douglas Fir Balk for Ponton Bridges, H. L. Bow¬ 

man, OEMsr-41, Drexel Institute of Technology, Philadel¬ 
phia, Pa., [February, 1942]. Div. 12-1310-MI 

Tests of Aluminum Balk 

2. Tests of Holloxa Metal Balk, H. L. Bowman, OEMsr-41, 

Drexel Institute of Technology, Philadelphia, Pa., July 
16, 1942. Div. 12-1320-MI 

3. Test of Aluminum Balk, H. L. Bowman, OEMsr-41, Drexel 
Institute of Technology, Philadelphia, Pa., July 15, 1944. 

Div. 12-1320-M2 

4. Test of Welded Specimens of Aluminum Alloy R303- 

T315, H. L. Bowman, Drexel Institute of Technology, 
Philadelphia, Pa., August 6 , 1944. Div. 12-1320-M3 

5. Deflection Test of Beam without and until Web Holes, 
H. L. Bowman, OEMsr-41, Drexel Institute of Technology, 
Philadelphia, Pa., October 31, 1944. Div. 12-1320-M I 

6 . Used 8" Aluminum Balk (61S-T), L. I*. Mains, OEMsr-41, 

Drexel Institute of Technology, Philadelphia, Pa., No¬ 
vember 10, 1944. Div. 12-1320-M5 

7. Test of Heavy Aluminum Balk (61S-T), L. P. Mains, 

OEMsr-41, Drexel Institute of Technology, Philadelphia, 
Pa., November 22, 1944. Div. 12-1320-M6 

8 . Test of Normal Aluminum Balk, 61S-T, until Internal Rib, 
L. P. Mains, OEMsr-41, Drexel Institute of Technology, 
Philadelphia, Pa., December 5, 1944. Div. 12-1320-M7 

9. Tests of Heavy 9x9" Aluminum Balk of Alloy 61S-T, L. P. 

Mains, OEMsr-41. Drexel Institute of Technology, Phila¬ 
delphia, Pa., December 18, 1944. Div. 12-1320-M8 

10. Test of Normal Aluminum Balk, 61S-T, with Reinforcing 
Plates, L. P. Mains, OEMsr-41, Drexel Institute of Tech¬ 
nology, Philadelphia, Pa., December 23, 1944. 

Div. 12-1320-M9 

11. Test of Aluminum Balk (24S-T) with Internal Rib, L. P. 

Mains, OEMsr-41, Drexel Institute of Technology, Phila¬ 
delphia, Pa., January 13, 1945. Div. 12-1320-M10 


Tests of Balk Fasteners 

12. Tests of Welded Steel Balk Fasteners, H. L. Bowman, 

OEMsr-41, Drexel Institute of Technology, Philadelphia, 
Pa., (n.d.). Div. 12-1330-M3 

13. Test on Balk Fasteners for the 25-ton and 10-ton Ponton 

Bridges, H. L. Bowman, Drexel Institute of Technology', 
Philadelphia, Pa., June 30, 1942. Div. 12-1330-MI 

14. Tests on Cast Steel Balk Fasteners for 25-ton Ponton 
Bridge, H. L. Bowman, OEMsr-41, Drexel Institute of 
Technology, Philadelphia, Pa., March 17, 1943. 

Div. 12-1330-M2 

Tests of Bridge Bolts 

15. Tests on Heat-treated Steel Bolts for H-10 Portable 
Bridges, H. L. Bowman, OEMsr-41, Drexel Institute ot 
Technology, Philadelphia, Pa. [February, 1942]. 

Div. 12-1340-M2 

16. Tests on Man-Ten Steel Bolts for H-10 Portable Bridge, 
H. L. Bowman, OEMsr-41, Drexel Institute of Technology, 
Philadelphia, Pa., November 19, 1945. Div. 12-1340-MI 


Chapter 14 

TORPEDO PROTECTION FOR MERCHANT 
VESSELS 

General 

1. On Torpedo Net Defence Experiments Made to the Order 
of the Director of Scientific Research, Admiralty. Model 
Torpedo Firing Experiments against Nets of Small Non- 
slipping Mesh Designed to Stop Torpedo outside Net 
(Summary), J. L. Kent, The William Fronde Laboratory, 
National Physical Laboratory, Teddington, England, June 
10 , 1943. 

2. Net and Boom Defences (Navy Ordnance pamphlet No. 
636), (n. a.), U. S. Navy Department, Bureau of Ordnance, 
Washington, D. C., August 10, 1943. 

3. Behavior of an Anti-submarine Net in a Tideway. Report 
on First Series of Model Tests (Report No. R-84), C. E. 
Janes, Navy Department, David Taylor Model Basin, 
Washington, D. C., June 1943. 

4. [ Torpedo Net Defense on EC-2 Liberty Ships] (Final re¬ 

port), H. Bannerman and Alan P. Brickman, OEMsr-1077, 
American Steel and Wire Company, New Haven, Conn., 
February 28, 1945. Div. 12-1400-MI 

5. Torpedo Net Defense for Merchant Ships (Historical rec¬ 
ord), (n. a.), [March 19, 1945]. Div. 12-1400-M2 

Nets for Low-Speed Torpedoes 

6 . [Anti-torpedo Nets for Ships] T.N.D. Project Plan No. 1- 

1943, Gordon H. Bannerman, OEMsr-1077, symbol 3018, 
American Steel and Wire Company, New Haven, Conn., 
[October 15, 1943]. Div. 12-1410-MI 




KtaU.. 





348 


BIBLIOGRAPHY 


Nets for High-Speed Torpedoes 

7. Principles Underlying the Mechanical Action of Anti-tor¬ 

pedo Harbor Defense Nets, AMG-B memo No. 7, H. J. 
Greenberg, G. H. Handelman, and W. Prager, NDRC, 
Applied Mathematics Group, Brown University, Provi¬ 
dence, R. I., September 16, 1943. Div. 12-1420-MI 

8 . The Strain Energy Absorbed by an Anti-torpedo Harbor 

Defense Net, AMP memo No. 67.2; AMG-B memo No. 10. 
H. G. Greenberg and W. Prager, NDRC, Applied Mathe¬ 
matics Group, Brown University, Providence, R. I., Oc¬ 
tober 25, 1943. Div. 12-1420-M2 

9. The Strain Energy Absorbed by Certain Anti-torpedo Net 

Panels in Drop Tests, AMP memo 67.4 AMG-B memo 14, 
H. J. Greenberg, W. R. Heller, and I. Michelson, NDRC, 
Applied Mathematics Group, Brown University, Provi¬ 
dence, R. I., March 8 , 1944. Div. 12-1420-M3 

10. [Torpedo Net Defense] T.N.D. Project plan No. 3-1943, 

Gordon H. Bannerman, OEMsr-1077, symbol 3018, Amer¬ 
ican Steel and Wire Company, New Haven, Conn., June 
30, 1944. Div. 12-1420-M4 

11. [Torpedo Net Defense ] T.N.D. Project plan No. 4-1944, 

Gordon H. Bannerman, OEMsr-1077, symbol 3018, Amer¬ 
ican Steel and Wire Company, New Haven, Conn., [Sep¬ 
tember 25, 1944], ' Div. 12-1420-M5 

12. [Torpedo Net Defense ] T.N.D. Project plan No. 5-1944 

and No. 7-1944, Gordon H. Bannerman, OEMsr-1077, sym¬ 
bol 3018, American Steel and Wire Company, New Haven, 
Conn., January 15, 1945. Div. 12-1420-M6 

13. [Ships’ Anti-torpedo Nets ] T.N.D. Project plan No. 6-1944, 

Gordon H. Bannerman, OEMsr-1077, symbol 3018, Amer¬ 
ican Steel and Wire Company, New Haven, Conn., Febru¬ 
ary 1, 1945. Div. 12-1420-M7 

Protection Against Magnetic Torpedoes 

14. [Electrically Protected Torpedo Defense Nets] T.N.D. Proj¬ 

ect plan No. 2-1943, Gordon H. Bannerman, OEMsr-1077, 
symbol 3018, American Steel and Wire Company, New 
Haven, Conn., November 5, 1943. Div. 12-1430-MI 

15. S. I. C. Pistol, Rodney F. Simons, OSRD, London Office, 

England, February 17, 1944. Div. 12-1430-M2 

16. Preliminary Measurements of the Firing Characteristics of 
the German Magnetic Exploder Pi2C (Serial No. 57157, 
Captured enemy equipment No. CEE 5583, Task No. 17G, 
Naval Ordnance Laboratory Memorandum No. 5667), C. 
N. Mooers, Navy Department (Naval Ordnance Labora¬ 
tory), June 27, 1944. 

17. [Electrically Protected Torpedo Defense Nets; Tested by 

Means of SIC and Pi2C Pistols ] T.N.D. Project plan No. 
2-1943, W. T. Pierce, OEMsr-1077, symbol 3018, American 
Steel and Wire Company, New Haven, Conn., October 7, 
1944. Div. 12-1430-M3 

18. [Torpedo Firing ] General Instructions; Navigational Equip¬ 
ment, (n. a.), Electro-Protective Corporation, (n. d.). 

Sonar Detection of Torpedoes 

19. Submarine Detection by Explosive Sound Ranging . . . 
Results Obtained on a Series of Short Cruises between 


May, 1941 and December, 1941, R. W. King, T. H. John¬ 
son, and A. P. Crary, American Telephone and Telegraph 
Company, New York, N. Y., [January 1942]. 

20. Tests on the Electro-Protective Corporation] Torpedo De¬ 
tector (Report No. P20/R1050) (Supplement to: Mer¬ 
chant vessel protection; sonic detection of torpedoes from 
merchant ships. New London Laboratory report P20/- 
R 688 ), W. B. Snow and E. E. Teal), OEMsr-20 and OEMsr- 
1128, U. S. Navy Underwater Sound Laboratory, Fort 
Trumbull, New London, Conn., November 15, 1944. 

21. Merchant Vessel Protection. An Evaluation of Means of 
Providing Protection for Merchant Vessels against Torpedo 
Attack (Report No. P20/R1216), W. B. Snow, D. A. 
Proudfoot, and E. E. Teal, OEMsr-1128, U. S. Navy Under¬ 
water Sound Laboratory, Fort Trumbull, New London, 
Conn., November 30, 1944. 

22. Merchant Vessel Protection. Sotiic Detection of Torpedoes 
from Merchant Ships, P20/R688, W. B. Snow and D. A. 
Proudfoot, OEMsr-1128, U. S. Navy Underwater Sound 
Laboratory, Fort Trumbull, New London, Conn., Febru¬ 
ary 3, 1944. 

High-Speed Underwater Photography 

23. Underwater Photography (Progress report), D. E. Kirk¬ 
patrick, J. Lamar Worzel, and Maurice Ewing. 

and 

Underwater Photography (Supplementary progress re¬ 
port), Edward M. Thorndike, C4-sr31-087, Woods Hole 
Oceanographic Institution, Woods Hole, Mass., May 4, 

1942. 

24. Instruction Manual for the Use of the Underwater Camera, 
J. Lamar Worzel and Maurice Ewing, OSRD NO-100, Sec¬ 
tion No. 6.1-sr31-740, Woods Hole Oceanographic Institu¬ 
tion, Woods Hole, Mass., March 16, 1943. 

25. Stereoscopic Use of Underwater Cameras, D. E. Kirkpat¬ 
rick, OSRD NO-100, Section No. 6.1-31-755, Woods Hole 
Oceanographic Institution, Woods Hole, Mass., August 25, 

1943. 

Chapter 15 

LAND COMBAT VEHICLES 
Turtle 

1. Track-laying Vehicle Development (Revised), [Roger S. 

Warner, Jr.], June 26, 1942. Div. 12-1510-M1 

2. Wheeled Vehicle Development, [Roger S. Warner, Jr.], July 

4, 1942. Div. 12-1510-M2 

3. Turtle; Tentative Organization, Roger S. Warner, Jr., 
[NDRC, Section C-2], Washington, D. C., July 30, 1942. 

Div. 12-1510-M3 

IVI Tank 

4. IVI Designs. Observations of Results of .30-caliber Ma¬ 
chine-gun Fire on the M3 Medium Tank, Roy W. Cum¬ 
mings, United Shoe Machinery Corporation, Research Divi¬ 
sion, Beverly, Mass., October 8 , 1941. Div. 12-1511-MI 


ryjMTzu. 




BIBLIOGRAPHY 


34!) 


Baker Tank 

5. Improvement Possibilities for Combat Vehicles (Confiden¬ 
tial engineering report No. 51), J. G. Baker, Baker Manu¬ 
facturing Company, Evansville, Wis., May 25, 1942. 

Div. 12-1512-MI 

6 . Description of Proposed Experimental Chassis and Some 
Adaptations for Proposed Combat Vehicle (Confidential 
engineering report No. 52), J. G. Baker, Baker Manufac¬ 
turing Company, Evansville, Wis., June 19, 1942. 

Div. 12-1512-M2 

7. A Summary of Developments in High Velocity Guns, W. C. 
Abhau, Lt. USN, confidential memorandum transmitted to 
OSRD by the Coordinator of Research and Development, 
Navy Department, July 27, 1942. 

8 . Camber, Caster, Toe-in, and King Pin Inclination on 

Steered Wheels (Engineering report No. 58), Marlin S. 
Baker, Baker Manufacturing Company, Evansville, Wis., 
August 26, 1942. Div. 12-1512-M3 

9. Transportation of a Combat Vehicle by Air (Engineer¬ 
ing report No. 60), Marlin S. Baker, Baker Manufacturing 
Company, Evansville, Wis., September 21, 1942. 

Div. 12-1512-M4 

10. Evaluation of the Wightman Pneumatic Suspension (En¬ 
gineering report No. 61), Arthur I. Chalfant, Baker Manu¬ 
facturing Company, Evansville, Wis., September 30, 1942. 

Div. 12-1512-M5 

11. A Study of Methods of Minimizing the Effects of Recoil in 

a Light Gun Carrying Vehicle (Engineering report No. 
63), Arthur I. Chalfant, Baker Manufacturing Company, 
Evansville, Wis., November 5, 1942. Div. 12-1512-M6 

12. An Evaluation of Three Special Combat Vehicles for At¬ 

tack and Defense (Engineering report No. 64), Marlin S. 
Baker, Baker Manufacturing Company, Evansville, Wis., 
(n. d.). Div. 12-1512-M14 

13. An Investigation of Jumping as a Means of Negotiating 

Obstacles (Engineering report No. 68), Arthur I. Chal¬ 
fant, Baker Manufacturing Company, Evansville, Wis., 
February 15, 1943. Div. 12-1512-M7 

14. Accumulator Bladder Protecting Device (Engineering re¬ 

port No. 70), J. G. Baker, Baker Manufacturing Company, 
Evansville, Wis., March 8, 1943. Div. 12-1512-M8 

15. The Hydraulic System of the One-wheel Test (Restricted 

engineering report No. 80), Arthur I. Chalfant, Baker 
Manufacturing Company, Evansville, Wis., October 20, 
1943 . ' ' Div. 12-1512-M10 

16. The Effect of the Recoil of a 75-mm Gun on an Eight-ton 

Vehicle (Engineering report No. 72), Arthur I. Chalfant, 
Baker Manufacturing Company, Evansville, Wis., March 
10, 1943. Div. 12-1512-M9 

17. A Combat Vehicle of High Mobility Designed for Trans¬ 

portation by Air (Restricted engineering report No. 96), 
J. G. Baker, OEMsr-524, Baker Manufacturing Company, 
Evansville, Wis., June 20, 1944. Div. 12-1512-M11 

18. Comparison between British Vehicle and Vehicle Pro¬ 

posed under Contract No. OEMsr-524, [J. G. Baker], Baker 
Manufacturing Company, Evansville, Wis., [August 30, 
1944 ]. Div. 12-1512-M12 


19. One-wheel Performance Test of a Proposed Combat Ve¬ 
hicle (Restricted engineering report No. 97), Arthur I. 
Chalfant, Baker Manufacturing Company, Evansville, Wis., 
September 5, 1944. ' Div. 12-1512-M13 

Chapter 16 

LAND VEHICLE COMPONENTS 

1. [Gun Turret Design for Light and Medium Tanks (Prog¬ 

ress report to November 1, 1941)], Clifford Roberts, NDCrc- 
204 and OEMsr-112, United Shoe Machinery Corporation, 
Boston, Mass., November 7, 1941. Div. 12-1600-MI 

2. [Gun Turret Design for Light and Medium Tanks (Final 

report)], Clifford Roberts, NDCrc-204 and OEMsr-112, 
United Shoe Machinery Corporation, Boston, Mass., June 
30, 1942. Div. 12-1600-M2 

3. The Design and Testing of a Centrifugal Air Cleaner 
(File No. 59A-HSB-11), H. S. Barnaby, OEMsr-133, The 
Sharpies Corporation, Philadelphia, Pa., July 29, 1942. 

Div. 12-1600-M3 

4. Completion of the Design and Testing of a Centrifugal Air 

Cleaner (File No. 59A-HSB-13), H. S. Barnaby, OEMsr- 
133, The Sharpies Corporation, Philadelphia, Pa., Febru¬ 
ary 8, 1943. Div. 12-1600-M4 

5. DUKW Tests with Barrage Rockets (Summary; CIT, 
OHC 1), L. A. Richards, California Institute of Technol¬ 
ogy, Pasadena, Calif., February 25, 1943. Div. 12-1600-M5 

6 . Photographs, Subject: Launchers for DUKW, General Mo¬ 
tors Corporation, Detroit, Mich., June 28, 1943. 

Div. 12-1600-M6 

7. CIT Type 6 Mod. 1 Launcher for the 4”.5 Barrage Rocket, 
120-barrel for 2i/ 2 -ton 6x6 Amphibious Truck, DUKW, 
(n. a.), OEMsr-418, California Institute of Technology 
(CIT Launcher Group), Pasadena, Calif., November 10, 
1943. 

8 . CIT Type 7 Mod. 1 Launcher for 7".2 Rockets, 42-rail for 
2i/ 2 -ton 6x6 Amphibious Truck, DUKW, A. S. Gonld, 
OEMsr-418, California Institute of Technology (CIT 
Launcher Group), Pasadena, Calif., February 4, 1944. 

Chapter 17 

LAND VEHICLE STUDIES 
Tank Noise Reduction 

1. Sound Levels inside and outside Marmon-Herrington 
Tanks (Progress report of Project I), L. L. Beranek, H. 
W. Rudmose, and R. L. Brown, Harvard University, Cruft 
Laboratory, Cambridge, Mass., June 30, 1941. 

Div. 12-1710-MI 

2. Reduction of the Noise from the Engine Compartment of 

an M-3 Light Tank (Report No. PG. 2.232), Paul Huber, 
General Motors Corporation (Acoustical Laboratory), Mil¬ 
ford, Mich., August 15, 1941. Div. 12-1710-M2 

3. Muffler Study on M-3 Light Tank (Report No. PG. 2.272), 
Paul Huber, General Motors Corporation (Acoustical Lab¬ 
oratory), Milford, Mich., October 27, 1941. 

Div. 12-1710-M3 








350 


BIBLIOGRAPHY 


4. Noise Tests on Mark III, “Valentine” Tank (Report No. 

PG. 2.285), Paul Huber, General Motors Corporation 
(Acoustical Laboratory), Milford, Mich., November 21, 
1941. Div. 12-1710-M4 

5. [Tank Track No/se] (Progress report No. PG. 2.291, Novem¬ 

ber, 1941), Paul Huber, OD-19, General Motors Corpora¬ 
tion (Acoustical Laboratory), Milford, Mich., November 
28, 1941. ' Div. 12-1710-M5 

6. Goodrich Band Track o?i White Half Track (Report 

No. PG. 2.290), Paul Huber, General Motors Corporation 
(Acoustical Laboratory), Milford, Mich., November 28, 
1941. Div. 12-1710-M6 

7. Analysis of Mufflers on Tanks as Related to Tactics (Re¬ 

port No. PG. 2.303), Paul Huber, General Motors Corpo¬ 
ration (Acoustical Laboratory), Milford, Mich., December 
19, 1941. Div. 12-1710-M7 

8. Tactical Value of Tank Noise Reduction (Report No. 

PG. 2.304), Paul Huber, General Motors Corporation 
(Acoustical Laboratory), Milford, Mich., December 22, 
1941. Div. 12-1710-M8 

9. Recommendations on Quieting Tanks (Report No. PG. 
2.330), Paul Huber, General Motors Corporation (Acous¬ 
tical Laboratory), Milford, Mich., March 17, 1942. 

Div. 12-1710-M9 

10. Summary of Noise Investigation on M-3 Light Tank No. 

909 (Report No. PG. 2.336), Paul Huber, General Motors 
Corporation (Acoustical Laboratory), Milford, Mich., 
April 4, 1942. Div. 12-1710-M10 

11. Noise in the Crete Compartment of M-3 Light Tank No. 

6305 (Report No. PG. 2.337), Frank W. Hayward, Gen¬ 
eral Motors Corporation (Acoustical Laboratory), Milford, 
Mich., April 29, 1942. Div. 12-1710-MI 1 

12. Supplementary Muffler Report (Report No. PG. 2.305), 
Richard O. Painter, General Motors Corporation (Acous¬ 
tical Laboratory), Milford, Mich., April 29, 1942. 

Div. 12-1710-M12 

13. Sprocket Noise Investigation on M-3 Light Tank No. 6305 
(Serial No. 909) (Report No. PG. 2.343), Frank W. Hay¬ 
ward, General Motors Corporation (Acoustical Labora¬ 
tory), Milford, Mich., May 4, 1942. Div. 12-1710-M13 

14. Approach Noise Tests on M-3 Light Tajik No. 6305 (Serial 

No. 909) (Report No. PG. 2.338), Frank W. Hayward, Gen¬ 
eral Motors Corporation (Acoustical Laboratory), Milford, 
Mich., May 14, 1942. Div. 12-1710-M14 

15. Track Noise and Vibration Tests on M-3 Light Tank No. 
6305 (Serial No. 909) (Report No. PG. 2.356), Frank W. 
Hayward, General Motors Corporation (Acoustical Lab¬ 
oratory), Milford, Mich., May 16, 1942. Div. 12-1710-N115 

16. Theory and Design of Rectangular Sound-Absorbing Ducts 

(Report No. PG. 2.371), Martin Hebert, Jr., General Mo¬ 
tors Corporation (Acoustical Laboratory), Milford, Mich., 
June 17, 1942. Div. 12-1710-M16 

Reduction of Bouncing in Towed Gun Carriages 

17. Behavior during Towing of and Suggested Design Changes 
for Two- and Four-wheel Gun Carriages (Confidential 


engineering report No. 57), J. G. Baker, Baker Manufac¬ 
turing Company, Evansville, Wis., August 7, 1942. 

Div. 12-1720-MI 

Chapter 18 

MISCELLANEOUS DEVICES 
Landing Wheel Brakes 

1. Unconfirmed Minutes of a Meeting of the SAE-NRC Air¬ 

craft Brake Survey Committee, Dayton, Ohio, C. E. Stryker, 
February 10, 1941. Div. 12-1810-MI 

2. Report of Aircraft Brake Survey Committee, C. E. Stryker, 

The Society of Automotive Engineers, Inc., New York, 
N. Y„ [May 20, 1941], Div. 12-1810-M2 

3. Aircraft Brakes [bibliography], The Society of Automotive 
Engineers, Inc., New York, N. Y., May 20, 1941. 

(Ref. 3, p. 289, should read 12.) Div. 12-1810-M3 

4. Report of Aircraft Brake Survey Committee, C. E. Stryker, 

The Society of Automotive Engineers, Inc., New York, 
N. Y„ June 10, 1941. Div. 12-1810-M4 

5. Aircraft Brakes Survey (memorandum of interviews), 

Herbert B. Lewis, National Research Council (Division of 
Engineering and Industrial Research), Washington, D. C., 
August 7, 1941. Div. 12-1810-M5 

6. Meeting on Aircraft Brake Materials, Dayton, Ohio, Her¬ 

bert B. Lewis, National Research Council (Division of En¬ 
gineering and Industrial Research), Washington, D. C., 
November 11, 1941. Div. 12-1810-M7 

7. Conference on Heat Generation and Transfer in Aircraft 
Brakes, Cleveland, Ohio, Herbert B. Lewis, National Re¬ 
search Council (Division of Engineering and Industrial 
Research), Washington, D. C., June 24, 1942. 

Div. 12-1810-M8 

8. Ail craft Brakes (Progress reports), Herbert B. Lewis, Na¬ 

tional Research Council (Division of Engineering and In¬ 
dustrial Research), Washington, D. C., September, 1941- 
February, 1943. Div. 12-1810-M6 

9. Aircraft Brakes (Final report), W. F. Durand and W. H. 

Kenerson, National Research Council (Division of Engi¬ 
neering and Industrial Research), Washington, D. C., May 
1, 1943. Div. 12-1810-M9 

Bomb Racks 

10. Standard Tests for Bomb Racks and Bomb Shackles, (n. a.). 
War Department (Bureau of Ordnance), Washington, 
D. C., November 15, 1943. 

11. Mark 51 Bomb Rack Investigations [(Progress report Nos. 
1-4, 6-27)], R. H. Cocks and C. E. Osgood, Douglas Aircraft 
Company, El Segundo, Calif., April 4, 1944-October 7, 1944. 

Div. 12-1820-MI 

12. Investigation and Redesign of Mark 51 Mod. 7 Bomb Rack 

(Final report No. ES-6688), C. E. Osgood, OEMsr-1435, 
Douglas Aircraft Company, El Segundo, Calif., November 
24, 1944. Div. 12-1820-M2 

13. Bomb Rack Mark 51 Mod. 0 (Final report), (n. a.), 

OEMsr-1333, I-T-E Circuit Breaker Company, Philadel¬ 
phia, Pa., [December 20, 1944]. Div. 12-1820-M3 


CO 



BIBLIOGRAPHY 


351 


Automatic Gages 

14. Screw Threads. A Bibliography of Available Material on 
Screw Thread Theory, Standards, Production Methods and 
Gaging Methods, Jones & Lamson Machine Company, 
Springfield, Vt., and Bryant Chucking Grinder Company, 
Springfield, Vt., OEMsr-497, July 1942. Div. 12-1830-M1 

15. Thread Gage Manufacture. A Monograph on Manufactur¬ 
ing Methods for the Production of Plug and Ring Thread 
Gages, Douglass Hawks, Jr., OEMsr-497; OD-49, Jones & 
Lamson Machine Cornany, Springfield, Vt., April 1943. 

Div. 12-1830-M2 

16. Thread Gage Development (Final report), Paul A. Gro- 
bety, Bryant Chucking Grinder Company, Springfield, Vt., 
OEMsr-497; OD-49. [January 25, 1945]. Div. 12-1830-M3 

Pneumatic Tire Substitutes 

17. Pneumatic Tire Substitutes (Interim report), S. Murray 

Jones, NDRC, Section C-2; QMC-6, New York, N. Y„ [Oc¬ 
tober 1942]. ~ Div. 12-1840-MI 

18. Operating Characteristics of the Martin Resilient Wheel 

Spoke (Report No. 40), J. C. Little and R. H. Neill. Amer¬ 
ican Steel and Wire Company, New Haven. Conn., October 
22, 1943. Div. 12-1840-M2 

19. Operating Characteristics of the Martin Resilient Wheel 

Spoke (Report No. 40A), J. C. Little and R. H. Neill. 
American Steel and Wire Company, New Haven, Conn., 
November 29, 1943. Div. 12-1840-M3 

20. Development and Performance of Three Types of Non- 

pneumatic Lightweight Resilient Tires, E. E. Sayre, Mar¬ 
tin Aeroplane Development Laboratory, Inc., Paramus, 
N. J., February 1, 1944. Div. 12-1840-M4 

21. Pneumatic Tire Substitutes (Final report), S. Murray 

Jones, NDRC, Division 12; OD-96, New York, N. Y., Oc¬ 
tober, 1944. Div. 12-1840-M5 

Emergency Rescue Equipment 

22. Experimental Seven Man Pneumatic Life Raft No. 1, 
S. Murray Jones and Harold M. Simmons, NE-102, Spark¬ 
man & Stephens, Inc., New York, N. Y., [April, 1944]. 

Div. 12-1850-M2 

23. Air-borne Life Boat (Final report), Harold M. Simmons, 

NE-101. Sparkman & Stephens, Inc., New York, N. Y., April 

28, 1944. Div. 12-1850-MI 

Rain-Repellent Coatings and Antifogging 
Methods 

24. Togging of Vision Devices under Flight Conditions, (n. a.), 

OEMsr-436, National Research Corporation, Boston, Mass., 
[August 17, 1942]. Div. 12-1860-MI 

25. Air Conditioning as a Means of Eliminating Fog and Frost 

Formation on Glass Surfaces in Optical Instruments, 
(n. a.), OEMsr-436, National Research Corporation, Bos¬ 
ton, Mass., October 8, 1942. Div. 12-1860-M2 


26. [ Vision Surfaces under Conditions of Rain and Icing, and 
Prevention of Frost-formation ] (Progress report No. 392 
for January, 1943), F. C. Benner, OEMsr-436, National Re¬ 
search Corporation, Boston, Mass., February 4, 1943. 

Div. 12-1860-M5 

27. [Easily Applied Rain-repellent Coatings, a Study of Liquids 

for Use as Non-inflammable De-icing Fluids, and Studies 
on the Formation and Prevention of Frost on Vision Sur¬ 
faces] (Progress report for February-March, 1943), (n. a.), 
OEMsr-436, National Research Corporation, Boston, Mass., 
[April 1943]. Div. 12-1860-M6 

28. [Rain Repellent Coalings for Vision Devices, and Testing 
Procedures for the Evaluation of Rain Repellent Coatings] 
(Progress report for April-May 1913), (n. a.), OEMsr-436, 
National Research Corporation, Boston, Mass., [June 1943]. 

Div. 12-1860-M7 

29. Rain-repellent Coatings as an Aid to Visibility through 

Vision Devices, (n. a.), OEMsr-436, National Research Cor¬ 
poration, Boston, Mass., [1913]. Div. 12-1860-M3 

30. [Fogging of Vision Surfaces, the Rain Problem and the 

Icing Problem on Windshield Surfaces] (Summary report), 
(n. a.), OEMsr-436, National Research Corporation, Boston, 
Mass., [1943]. Div. 12-1860-M4 

31. Flight Tests of Anti-fogging Compounds (Final report), 

Lt. R. W. De Moss and Lt. J. M. Kirchberg, TED No. 
PTR-2550, LI. S. Naval Air Station, Patuxent River, Md., 

July 20, 1944. Div. 12-1860-M8 

Sine-Disc Propeller 

32. Sine-Disc Propeller Investigation (Final report), Douglas 

Van Patten, OEMsr-1188, F. L. Jacobs Company, Detroit, 
Mich., November 9, 1944. Div. 12-1880-MI 

33. Sine Disc Propeller Work (Final report Sparkman & 
Stephens job. No. 467), Olin J. Stephens II, OEMsr-154, 
Sparkman S: Stephens, Inc., New York, N. Y., June 30, 1945. 

Div. 12-1880-M2 

Chapter 19 

MISCELLANEOUS STUDIES 
Turning Basin Research 

1. Model Experiments on the Effect of Relative Propeller 

Speeds upon Turning of High-speed Tunn-screw Ships 
(Technical memorandum No. 63), John B. Drisko and 
Anthony Suarez, Stevens Institute of Technology, Hoboken, 
N. J„ July 22, 1942. Div. 12-1910-M2 

2. The Effect of Bilge Keels on Turning of a Destroyer Model 
Having Twin Rudders (Technical memorandum No. 
65), John B. Drisko, C.7-sr458-534, Stevens Institute of Tech¬ 
nology, Hoboken, N. J.. October 21, 1942. Div. 12-1910-M3 

3. The No. 2 Tank for Maneuvering Tests (Technical mem¬ 

orandum No. 64), Kenneth S. M. Davidson and John B. 
Drisko, OEMsr-458, OSRD No. 1039, C,7-sr458-440, Stevens 
Institute of Technology, Hoboken, N. J., November 6, 
1942. Div. 12-1910-M4 







352 


BIBLIOGRAPHY 


1. Turning Tests of Ship Models (Bi-weekly reports cover¬ 
ing period prior to July 11, 1942, and from July 11 to De¬ 
cember 26, 1942), (n. a.), OEMsr-458, Stevens Institute of 
Technology, Hoboken, N. J., July 11-December 26, 1942. 

Div. 12-1910-M1 

5. Effect upon Destroyer Turning Circles of a Tin Protector 

for the Sound Dome (Report No. 230). Kenneth S. M. 
Davidson and John B. Drisko, OEMsr-458; 12-sr458-441, 
Stevens Institute of Technology, Hoboken, N. J., February 
3, 1943. Div. 12-19I0-M5 

6. Effect of Keel Fins of Exaggerated Size on Destroyer Turn¬ 
ing Circles (Report No. 237), John B. Drisko and John A. 
Hamer, OEMsr-458; 12-sr458-443, Stevens Institute of Tech¬ 
nology, Hoboken, N. J., March 17, 1943. Div. 12-1910-M6 

7. Effect of Relative Propeller Speeds upon Turning of De¬ 

stroyers with Twin Rudders (Report No. 240, supple¬ 
ments technical memorandum No. 63), John B. Drisko, 
[OEMsr-458]; 12-sr458-445, Stevens Institute of Technology, 
Hoboken, N. J„ March 25, 1943. Div. 12-1910-M7 

8. Turning Characteristics of a Series of Sixteen Destroyer 
Hulls, Stevens Models Nos. 450 to 465, Parts I and II, 
(Report No. 221), John B. Drisko, OEMsr-458-443, Stevens 
Institute of Technology, Hoboken, N. J., April 17, 1943. 

Div. 12-1910-M8 

9. Effect of Rudder Size on the Turning of a Destroyer Model 

with Twin Rudders (Report No. 241), John B. Drisko, 
OEMsr-458; 12-sr458-446, Stevens Institute of Technology, 
Hoboken, N. J., April 24, 1943. Div. 12-1910-M9 

10. The Influence of Afterbody Profile and Section Shape upon 
the Turning of Destroyer Models (Report No. 243), John 
B. Drisko, OEMsr-458; 12-sr458-447, Stevens Institute of 
Technology, Hoboken, N. J.. May 29, 1943. 

Div. 12-1910-M 10 

11. Effect of Unlike Rudder Angles upon Turning of Destroy¬ 
ers until Twin Rudders (Report No. 238), John B. Drisko 
and John A. Hamer, OEMsr-458; 12-sr458-444, Stevens In¬ 
stitute of Technology, Hoboken, N. J., June 21, 1943. 

Div. 12-1910-MI 1 

12. Turning Tests of Thirteen V-bottom Destroyer Models. 

Stevens Models Nos. 470-481 (Report No. 253), (n. a.), 
OEMsr-458-449, Stevens Institute of Technology, Hoboken, 
N. J., December 31, 1943. Div. 12-1910-M12 

13. Minimum Turning Circles and Steering Relating Princi¬ 

pally to Naval Vessels of Generally Conventional Types 
(Summary for turning and steering discussion), Kenneth 
S. M. Davidson, Stevens Institute of Technology, Hoboken, 
N. J., March 1, 1944. Div. 12-1910-M13 

14. Further Notes on Turning and Steering (Notes No. 8; a 

continuation of N-7, dated March 1, 1944), Kenneth S. M. 
Davidson, Stevens Institute of Technology, Hoboken, N. J., 
March 13, 1944. Div. 12-1910-M14 

15. Concerning the Coordination of Kinematic Data on the 

Turning Characteristics of Ships (Technical memoran¬ 
dum No. 69), Kenneth S. M. Davidson and John B. Drisko, 
OEMsr-458; 12-sr458-448, Stevens Institute of Technology, 
Hoboken, N. J., March 15, 1944. Div. 12-1910-M 15 

16. Some Evidence Regarding the Influence of Hull Profile on 
the Turning of Destroyer Models (Report No. 257), John 
B. Drisko, OEMsr-458; sr458-450, Stevens Institute of Tech¬ 
nology, Hoboken, N. J., March 20, 1944. Div. 12-1910-M16 


17. Effect of Shallow Water upon Turning (Report No. 263), 
John B. Drisko, OEMsr-458; sr458-451, Stevens Institute of 
Technology, Hoboken, N. J., May 15, 1944. 

Div. 12-1910-M17 

18. Effect of Relative Propeller Speeds upon Turning of Four- 
screw Single-rudder Ships (Report No. 266), John B. 
Drisko and John A. Hamer, OEMsr-458; sr458-454, Stevens 
Institute of Technology, Hoboken, N. J., June 10, 1944. 

Div. 12T910-M18 

19. Resistance and Turning Characteristics of Two Round- 
bottom Destroyer Hulls (Stevens Models No. 586 and 
587) (Report No. 265; an extension of report No. 221), 
John B. Drisko, OEMsr-458; sr-458-452, Stevens Institute of 
Technology, Hoboken, N. J., July 18, 1944. 

Div. 12-1910-M19 

20. Exploratory Investigation of Static Steering Stability and 

Initial Turning Moment cn Ship Models (Report No. 
270), William H. Sutherland, OEMsr-458; OEMsr-458-455, 
Stevens Institute of Technology, Hoboken, N. J., Novem¬ 
ber 1914. Div. 12-1910-M20 

21. Resistance of V-bottom Hulls at Speed-length Ratios up to 

5 (Report No. 264), John B. Drisko, OEMsr-458; sr458- 
453, Stevens Institute of Technology. Hoboken, N. J., De¬ 
cember 1914. Div. 12-1910-M21 

22. Exploratory Investigation of the Lateral Components of 

Forces Acting on Ship Models in Steady Turning (Report 
No. 271), William H. Sutherland, OEMsr-458; sr458-456, 
Stevens Institute of Technology, Hoboken, N. J., January 
1945. Div. 12-1910-M22 

23. Construction and Operation of Maneuvering Tank for In¬ 

vestigation, by Models, of Ship Turning Characteristics 
(Final report No. 283), John B. Drisko, OEMsr-458; sr458- 
459, Stevens Institute of Technology, Hoboken, N. J., Feb¬ 
ruary 1945. Div. 12-1910-M23 

Cavitation Research 

24. Final Bi-monthly Project Reports (Division 12 and Section 

12.1) (No. 10), National Defense Research Committee, De¬ 
cember 1, 1944. Div. 12-0100-MI 

Snow Studies 

25. Measurements of Snoiv Properties in August, 1942, and a 

Few Applications of Them (September 16, 1942), Herman 
Mark, Polytechnic Institute of Brooklyn, Brooklyn, N. Y., 
September, 1942. Div. 12-1920-MI 

26. Development of Weasel with Notes on Problems of Its Use, 
P. C. Putnam, NDRC, Section C.-2, Oct. 14, 1942. 

Div. 12-0510-M5 

27. The Investigation of Snow Properties during October, 1942 
on the Columbia Ice Fields, (n. a.). Polytechnic Institute 
of Brooklyn, Brooklyn, N. Y., October 28, 1942. 

Div. 12-1920-M2 

28. Brief Chronological History of the Development Program 

of T-15 between May 17, 1942 and November 2, 1942. 
Contains: Dr. H. Mark’s Report and Curves on Snow Con¬ 
ditions, T-15 Specifications and Pictures of the Completed 
Vehicle, Sequence of Pictures from Highway to Syiowfield, 
Vol. Ill, (n. a.), Studebaker Corporation, South Bend, Ind., 
November 2, 1942. Div. 12-0510-M9 



BIBLIOGRAPHY 


353 


29. Development of II easel, with Notes on Problems of Its Use 

(Interim report), P. C. Putnam, Section C-2, NDRC, No¬ 
vember 2, 1942. Div. 12-0510-M6 

30. Coordinated Snow and Weather Observations Carried Out 

at Various Locations from January to May, 1943 (Final 
report), Herman Mark, Polytechnic Institute of Brooklyn, 
Brooklyn, N. Y„ June 1913. Div. 12-1920 M3 

Wake Visibility and Its Suppression 

31. Instructions for Camouflaging the 11 ake of Amphibian 
Truck, DUKW-353, (n. a.), Woods Hole Oceanographic 
Institution, Woods Hole. Mass., [1943]. Div. 12-1930-MI 

32. Wake Visibility atid Its Suppression (Final report), 

George I,. Clarke, OEMsr-870, GMC Truck & Coach Divi¬ 
sion, General Motors Corporation, Detroit, Mich., March, 
1943. Div. 12-1930-M2 

33. Methods for Reducing and Obscuring the Wake of Surface 

Vessels (Revised memorandum), George L. Clarke, 
Woods Hole Oceanographic Institution, Woods Hole, 
Mass., May 18, 1943. Div. 12-1930-M3 

Wind and Wave Studies 

34. Handbuch der Ozeanographie, O. Kruemmel, Vol. I, Stutt¬ 
gart, 1907. 

35. Hydrodynamics of Wave Motion, H. Jeffreys, Phil. Mag. (0), 
48, 44 (1924). 

36. Dynarnische Ozeanographie, A. Defant, Berlin, 1929. 

37. Science of the Sea, G. H. Fowler, 2nd Edition. Oxford, 1930. 

38. Probleme der Wasserwellen, H. I horade, Henry Grand, 
Hamburg, 1931. 

39 . Oceanwaves and Kindred Geophysical Phenomena, \ . 
Cornish, Macmillan, New York, N. Y., 1934. 

40. Oceanography for Meteorologists, H. Sverdrup, Prentice 
Hall, New York, N. Y., 1942. 


II. The Measurements of Wind Velocity and Wave Character¬ 
istics, Cape Cod, Nov. 10-Dec. 7, 1042, Herman Mark, Poly¬ 
technic Institute of Brooklyn, Brooklyn, N. Y., December 
12.1942. Div. 12-1910 Ml 

Chapter 20 
SPECIAL PROJECTS 
10-Ton Missile 

1. Studies on the Gas liubble Resulting from Underwater 
Explosions. On the Best Location of a Mine near the Sea 
Bed (AMP report 37.1 R. AMG-NYU No. 49), Richard 
Courant, NDRC, Applied Mathematics Group, New York 
University, New York, N. Y.. May 194 1. Div. 12-2020-MI 

2. A Project to Sink the Japanese Fleet and to Destroy Jap¬ 

anese Industry, Palmer C. Putnam, Warren Weaver, and 
F. C. Collbohm, NDRC, Division 12, Boston, Mass., June 
1944. Div. 12-2020-M2 

3. Effectiveness of Near Miss Bombs against Warships, E. 
Bright Wilson, Jr., (Project No. 223), Woods Hole Oceano¬ 
graphic Institution (Underwater Explosives Research Lab¬ 
oratory), Woods Hole, Mass., June 23, 1944. 

Div. 12-2020-M3 

4. Special Weapons Suggested for Use against Certain Jap¬ 
anese Targets in the Near Future, Palmer C. Putnam and 
others, OSRD, Washington, D. C., July 13, 1944. 

Div. 12-2020-Ml 

5. Large Bomb for B-17 Plane (Project: “Egg"), Morris Dam 

Tests (Report No. 123), (n. a.), OEMsr-418, Section 4, Cali¬ 
fornia Institute of Technology, Pasadena, Calif., July 29, 
1944. Div. 12-2020-M5 

6. The Effect of Roughness of Sea on the Entry Angle of a 

Projectile (Morris Dam report No. 127), R. I. Piper, 
OEMsr-418, California Institute of Technology, Pasadena, 
Calif., August 19, 1944. Div. 12-2020-M6 


C 








OSRD APPOINTEES 


Division 12 
Chief 

Hartley Rowe 


Deputy Chief 

Ralph Douglas Booth 

Technical Aides 

James A. Britton Palmer Cosslett Putnam 
S. Murray Jones Roger Sherman Warner, Jr. 


Members 


Kenneth S. M. Davidson 
Lester M. Goldsmith 
Eugene James Reardon 


Henry E. Rossell 
Richard Henry Whitehead 
William L. Woodward 


Section 12.1 
Chief 

William Eredericr Durand 


Members 


James L. Bates 
William Hovgaard 


Ernest Rigg 

Kari. Ernest Schoenherr 







CONTRACT NUMBERS, CONTRACTORS, AND SUBJECT OF CONTRACTS 


Contract 

Number 

Name and Address 
of Contractor 

Subject 

Refer to 
Chapter 

NDCrc-41 

Carson & Carson 

Philadelphia, Pa. 

Investigation of design problems in connection with trestle 
bridges, portable bridges, portable overpasses, ponton 
bridges, and other Engineer Corps structures. 

12 

NDCrc-148 

National Research Council 
Washington, D. C. 

Development of a wheel brake drum and brake landing com¬ 
bination which will permit more energy' to be absorbed per 
unit of rubbing surface. Development of improved disk 
brakes. 

18 

NDCrc-204 

United Shoe Machinery Corp. 
Boston, Mass. 

Development and design of a gun turret for light and me¬ 
dium tanks. 

16 

OEMsr-26 

Edgerton, Germeshausen & Grier 
Cambridge, Mass. 

Development and study of high-speed pictures of drive 
mechanisms. 

17 

OEMsr-36 

Sparkman & Stephens, Inc. 

New York, N. Y. 

Preliminary studies of ferries, barges, and towboats. 

12 

OEMsr-41 

Drexel Institute of Technology 
Philadelphia, Pa. 

Investigation of design problems in connection with trestle 
bridges, portable bridges, portable overpasses, ponton 
bridges, and other Engineer Corps structures. 

11 

12 

13 

OEMsr-72 

American Steel & Wire Co. 

New Haven, Conn. 

Investigation and development of a pneumatic tire substitute. 

18 

OEMsr-112 

United Shoe Machinery Corp. 
Boston, Mass. 

Investigating improved tank vision devices. 

16 

OEMsr-133 

The Sharpies Corp. 

Philadelphia, Pa. 

Design, development, and testing of a centrifugal scourer for 
carburetor intakes to improve operation of tanks during 
sand storms. Development of testing techniques with par¬ 
ticular reference to particle size. 

16 

OEMsr-138 

T. R. Tarn 

Pittsburgh, Pa. 

Investigation of design problems in connection with ponton 
ferries. 

12 

OEMsr-154 

Sparkman & Stephens, Inc. 

New York, N. Y. 

Design, development, construction, and testing (1) 1,4-ton 
amphibious jeep, (2) airborne amphibious and nonam- 
phibious track-laying snow vehicles (Weasel), (3) 2i/2-ton 
amphibious truck (DUKW), (4) trailer for 2i/2*ton amphib¬ 
ious truck, and (5) related equipment, including engineer¬ 
ing and consulting services connected therewith. Develop¬ 
ment of an amphibious vehicle which can be used for rescue 
work over swamps and mud flats. Development of various 
models of military vehicles designed or converted for am¬ 
phibious use. Assist in study of sine-disk propeller. Investi¬ 
gate present rafts and submit designs of proposed modifica¬ 
tions of existing rafts and a comjiletely new designed raft 
which will hold essential equipment required by the per¬ 
sonnel while living on the raft and which will incorporate 
such additional comforts for the personnel as is possible 
without exceeding weight limitations. 

2 

3 

4 

5 

6 

7 

8 

9 

10 

18 

OEMsr-182 

Mai mon-Herrington 

Indianapolis, Ind. 

Development, construction, and testing of 1,4-ton amphibious 
jeep. 

9 

OEMsr-216 

Carson & Carson 

Philadelphia, Pa. 

Investigation or design problems in connection with trestle 
bridges, portable bridges, portable overpasses, ponton 
bridges, and other Engineer Corps structures. 

12 

OEMsr-436 

National Research Corporation 
Boston, Mass. 

Study of methods for minimizing the effects of fog, rain, sleet, 
frost, ice, dust, and other deposits upon optical and other 
transparent surfaces. 

18 




355 












CONTRACT NUMBERS, 

CONTRACTORS, AND SUBJECT OF CONTRACTS 
(Continued) 


Contract 

Number 

Name and Address 
of Contractor 

Subject 

Refer to 
Chapter 

OEMsr-458 

Trustees of the 

Stevens Institute of Technology 
Hoboken, N. J. 

Construction of testing tank and investigation of effect of 
various changes of hull form and loading on turning of 
ship models and Navy vessels. 

19 

OEMsr-460 

General Motors Corporation 
Detroit, Mich. 

Study of noise reduction in tanks. 

17 

OEMsr—481 

The Ford Motor Co. 

Dearborn, Mich. 

Development and construction of ultra-silent motor- 
generator. 

20 

OEMsr-487 

The Ford Motor Co. 

Dearborn, Mich. 

Development, construction, and testing of 14 -ton amphibious 
jeep. 

2 

OEMsr-497 

Jones & Lamson Machine Co. 
Springfield, Yt. 

Development of an inspection method to eliminate the use of 
thread, plug, and ring gages. Development of methods of 
thread gaging which will eliminate the use of thread, plug, 
and ring gages or which will minimize wear resulting in 
rapid deterioration of the gage as a precision instrument. 
Assembly of a comprehensive bibliography of screw thread 
gage theory, practice, and instruments. Development of one 
or more models of such gaging equipment. Printing and 
developing of 500 copies of a monograph on manufacturing 
methods for the production of plug and ring gages. 

18 

OEMsr-524 

Baker Manufacturing Company 
Evansville, Wis. 

Design, development, construction, and test of one or more 
full-scale pilot models of combat vehicles complementing 
established and proved characteristics with the most ad¬ 
vanced principles of design and development which may 
result from collaboration between interested branches of 
the Armed Services and leading technical, scientific, and 
industrial personnel. 

15 

17 

OEMsr-568 

Beyer and Tarn 

Pittsburgh, Pa. 

Investigation and development of a pneumatic tire substitute. 

18 

OEMsr-631 

Dr. Philip Newton 

New York, N. Y. 

Investigation and development of a pneumatic tire substitute. 

18 

OEMsr-635 

The Studebaker Corporation 
South Bend,Ind. 

Design, development, construction, and test of four full-scale 
pilot models of amphibious, airborne, track-laying snow 
vehicle, and of two full-scale pilot models of a nonamphib- 
ious, airborne, track-laying snow vehicle (T-15 Weasel). 
Assistance in acquisition and study of snow data. Develop¬ 
ment and construction of four modified snow vehicles (M-29 
Weasel). 

5 

19 

OEMsr-736 

Factory Products Company 
Dearborn, Mich. 

Investigation and development of a pneumatic tire substitute. 

18 

OEMsr-756 

William Allen Brown 
Philadelphia, Pa. 

Investigation and development of a pneumatic tire substitute. 

18 

OEMsr-757 

James Matthew MacLcan 
of Amich & Speier 

Detroit, Mich. 

Investigation and development of a pneumatic tire substitute. 

18 

OEMsr-758 

William E. Joor 

Houston, Texas 

Investigation and development of a pneumatic tire substitute. 

18 

OEMsr-775 

Ampat Corporation 

New York, N. Y. 

Investigation and development of a pneumatic tire substitute. 

18 










CONTRACT NUMBERS, CONTRACTORS, AND SUBJECT OF CONTRACTS 

(Continued ) 


Contract 

Name and Address 


Refer to 

Number 

of Contractor 

Subject 

Chapter 

OEMsr-802 

James V. Martin 

Investigation and development of a pneumatic tire substitute. 

18 


Rochelle Park, N. J. 



OEMsr-870 

CMC Truck & Coach Division 

Design, development, construction, and test of (1) one full- 



General Motors Corporation 

scale pilot model of a 2i/2-ton amphibious truck (DUKW), 



(Formerly Yellow Truck & Coach 

(2) one model of an amphibious trailer for use with the 2 1 / 2 - 



Manufacturing Company) 

ton amphibious truck, (3) installation of rocket launcher in 



Pontiac, Mich. 

DUKAVs in accordance with general function specifications 
furnished by Division 3 of NDRC, (4) a tank lilting ma¬ 
chine, (5) complete sets of accessory equipment for use of 
amphibious truck in ferrying tanks, other land vehicles 
and airplanes, (6) accessory equipment for use of the am¬ 
phibious truck as a bridge ponton, (7) automatic tire infla¬ 
tion aiid deflation device, (8) bow and stern wake-suppres¬ 
sion machine for use with the amphibious truck, (9) three 
sets of H-10 Armored Force Treadway Bridge, and (10) 

3 



assistance in study of bow and stern wake visibility and 

4 



possible suppression. Performance of such other work on 

17 



related equipment as may be requested. 

19 

OEMsr-878 

Polytechnic Institute of Brooklyn 

Development and study of snow data for the purpose of assist- 



Brooklyn, N. Y. 

ing in the design of snow vehicles, the possible forecasting 
of snow characteristics in theaters of operation, and the 
forecasting of vehicle performance in such theaters. 

19 

OEMsr-907 

Kelsey-Hayes Wheel Company 

Investigation and development of a pneumatic tire substitute. 

19 


Detroit, Mich. 



OEMsr-938 

Budd Wheel Company 

Investigation and development of a pneumatic tire substitute. 

19 


Detroit, Mich. 



OEMsr-1077 

American Steel & Wire Company 

Investigation of the design and operation of antitorpedo nets. 



New Haven, Conn. 

Development of suitable counter-counter methods. Delivery 
of improved designs or models or both. 

11 

OEMsr-1166 

The Stuclebaker Corp. 

Development of an amphibious vehicle which can be used for 



South Bend,Ind. 

rescue work over swamps and mud flats (M-29C Weasel). 

5 

OEMsr-1188 

F. L. Jacobs Company 

Design and construct Van Patten sine-disk propeller and run 



Detroit, Mich. 

comparative tests with device placed in craft installed by 
Navy. 

18 

OEMsr-1333 

ITE Circuit Breaker Company 

Studies and experimental investigations in connection with 



Philadelphia, Pa. 

the modification of the present Mark 51 bomb rack and de¬ 
velopment of a new bomb rack interchangeable with the 
Mark 51. Tests of such racks and such other related equip¬ 
ment as may be requested. 

18 

OEMsr-1344 

Sparkman & Stephens, Inc. 

Studies and experimental investigations in connection with 



New York, N. Y. 

harnessing and propelling amphibious explosive charges. 

9 

OEMsr-1435 

Douglas Aircraft Co., Inc. 

Studies and experimental investigations in connection with 



Santa Monica, Calif. 

the modification of the present Mark 51 bomb rack and 
development of a new bomb rack interchangeable with the 
Mark 51. Tests of such racks and such other related equip¬ 
ment as may be requested. 

18 

Symbol 4427 

Hydraulic Research Institute 

State University of Iowa 

Study of cavitation on water tank models. 

19 


Iowa City, Iowa 













SERVICE PROJECT NUMBERS 

The projects listed below were transmitted to the Executive Secretary, 
National Defense Research Committee [NDRC], from the War or Navy 
Department through either the War Department Liaison Officer for 
NDRC or the Office of Research and Inventions (formerly the Coordi¬ 
nator of Research and Development), Navy Department. 


Service 

Project. Refer to 

Number Subject Chapter 

AC-25 Survey and improvement of aircraft landing wheel brakes. 18 

AC-49 Study of methods for minimizing the effects of rain, fog, sleet, frost, ice, dust, and other 

deposits upon optical and other transparent surfaces. 18 

AC-60 Development of amphibious vehicle for use in rescue work over swamps and mud flats. 5 

AN-9 Studies and investigation of harnessing amphibious explosive charges. 9 

CE-1 Assistance in design and test of bridges and ferries. 11, 12, 13 

CE-20 Study of vehicle for use in demolition of key enemy-held facilities and in their restoration by 

friendly troops. 15 

MC-101 Development of a trailer hitch. 9 

NE-101 Design, development, and testing of improved airborne lifeboat. 18 

NE-102 Design, development, and testing of improved sailing rubber boat. 18 

NO-158 Development of improved antitorpedo nets and development of suitable counter-counter 

methods. . 14 

NO-158 Study of requirements for sound devices for merchant ships and development of sonar detect- 

(Merchant) ing devices for merchant vessels. 14 

NO-233 Redesign of navy bomb racks Mark 51 Mods. 6 & 7. 18 

NS-160 Design, construction, and testing of sine-disk propeller. 18 

NS-294 Study of cavitation on water tank models. 19 

OD-19 Study of devices and methods for the reduction of tank noise. 17 

OD-30 Development and design of turret gun mount for armored fighting vehicles. 16 

OD-40 Development of centrifugal air cleaners. 16 

OD-49 Development of thread inspection method which will eliminate the use of thread, plug, and 

ring gages. 18 

OD-60 Design, development, building, and testing of land combat vehicles. 1.5 

014-62 Assistance in development and procurement of equipment and devices for field conversion of 

the M-3 tank to eliminate cold starting difficulties. 18 

OD-64 Study of methods and devices for controlling the bouncing of towed artillery gun carriages. 17 

OD-65 Design, development, construction, and testing of airborne amphibious and nonamphibious 

track-laying snow vehicles; acquisition and study of snow data. 5 , 19 

OD-92 Design, development, construction, and testing of amphibious trailer for 214 -ton amphibious 

truck and of components of amphibious trailer. 8 , 9 

OD-92 (EXT) Design, development, construction, and testing of portable rocket launcher for DUKAV. 16 

OD-95 Design, development, construction, and testing of 14 -ton amphibious scout car (jeep). 2 

OD-96 Investigation and development of pneumatic tire substitutes. 18 


358 C 
















INDEX 


The subject indexes of all STR volumes are combined in a master index printed in 
a separate volume. For access to the index volume consult the Army or Navy agency 
listed on the reverse of the half-title page. 


Aero-Sled, 117, 130, 322 
Aerosol for anti-fogging, 309 
A-frame for loading tank-ferrying 
barges, 225 

Air cleaner for tank engines, 272 
Air desiccation device for anti-fogging, 
311 

Airborne lifeboats, 304 
Airborne life raft, 301 
Aircraft brakes, improved, 287 
Alligator (amphibious vehicle), 12 
American Steel and Wire Co., 240 
Ampat wheel, 298 

Amphibians, design principles, 179-197 
Amphibians, summary of uses, 195 
Amphibious cargo carrier, based on 
T-39 light tractor, 155 
Amphibious cargo carrier, 15-ton, 162 
Amphibious conversion equipment, 
165-170, 181 

Amphibious demolition charges, self- 
propelled, 170-171 
Amphibious gun carriages. 151-154 
Amphibious jeep, 6 

Amphibious paddle-wheel towboat, 227 
Amphibious trailer hitch, 168-170 
Amphibious trailers, 164 
Amphibious vehicles, jet-propelled, 177, 
197 

Amphibious vehicles, proposed, 158 
Amphibious Weasel; see Weasel 
Anchor for DUKW, 33 
Anti-fogging methods for glass surfaces, 
305-308; see also Rain-repellent 
coatings 

air desiccators, 311 
water-absorbents, 310 
wetting agents, 309 
Antitorpedo cables, 249 
Antitorpedo nets, 239-249 
Anzio, use of the DUKW, 87 
Applications of the DUKW, 65-113 
Aquacheetah, 180 

Archimedean screw-driven snow ve¬ 
hicles, 118. 119,322 

Ark (Weasel, model M29-C), 135-140, 
145-149 

Armament on DUKW, 52 
Armor protection for amphibians, 193 
Articulated ponton bridges, effect of 
loads, 203-213 

Assist-feed for .50-caliber machine gun 
(M4), 271 


Atlas-Habberstadt tire, 297 
Automatic thread gages, 292-296 

Baffles for wake visibility suppression, 
326 

Baker tank, 257 
Balk, aluminum, 233-237 
Balk, Douglas fir, 233 
Balk fasteners, 237 
Barges for tank-ferrying, 222-229 
BB devices for tank flotation, 166 
Beam-draft ratio, amphibians, 189 
Beams for military bridges, 233 
Bethlehem Steel Company portable 
bridges, 217 

Beyer and Tarn tire, 298 
Bilge pump design, DUKW, 23 
Blankenship device for tank flotation, 
166 

Blondin cable, 242 

Blondin roller for antitorpedo nets, 
251 

Bolts for bridges, 238 
Bomb, 10-ton, 332-335 
Bomb racks, 288 

Bombardier (amphibious vehicle), 117, 
130, 322 

Bombing, defense against, 336 
Bouncing reduction in gun carriages, 
283 

Bow for self-propelled amphibious de¬ 
molition charges, 170-171 
Brakes, aircraft, 287 
Bridge holts, 238 

Bridge component testing, 233-238 
Bridge designs; articulated, for 20-ton 
loads, 213 

articulated ponton, 203-212 
Bethlehem steel portable bridge, 217 
continuous ponton, 198-203 
Inglis bridge, 216 
portable 200-foot, 217 
portable railway bridge, 220 
60-ton tank ponton bridge, 215 
Sparkman & Stephens bridge, 220 
30-ton tank ponton bridge, 214 
treadway bridge, 218 
tube bridge, 216 
Bridge ramps, 220 
British Terrapin Mark I, 180 
British Terrapin Mark II, 180 
Brooklyn Polytechnic Institute, 317, 327 
Brown tire, 298 


Bruning Co., Charles, 336 

Budd tire, 298 

Budd wheel, 297 

Burma, use of the DUKW, 106 

Cables, use against torpedoes, 249 
California Institute of Technology, 332 
Cargo carriers; amphibious 15-ton, %- 
track, 162 

light amphibious, 155 
M-28 (T-15) Weasel, 117-132, 140 
M-29 (T-24) Weasel, 132-135 
M-29C Weasel, 135-140, 145-149 
Cargo-handling equipment of the 
DUKW, 42-49 

Cargo-handling technique with the 
DUKW, 13, 76, 84-106, 112 
Carson & Carson, 213 
Casualty evacuation with DUKWs, 77 
Casualty evacuation with Weasel, 143 
Caterpillar tractors, 118 
Cavitation research, 316 
CCKW General Motors truck, 16 
Centrifugal air cleaner for tank and 
truck engines, 272 

Climbing ability of vehicles in snow, 321 
Clips for antitorpedo nets, 241 
Cold-weather starting of tank engines, 
313 

Compass for tanks, 336 
Control system for DUKW, 77 
Conversion design for amphibious ve¬ 
hicles, 181 

Cooling system. DUKW engine, 26 
Coral reef operation of DUKW, 37 
Cruft Laboratory, Harvard University, 
278 

Cunningham, Son & Co., James, 168 

Dams, air attack on, 335 
DD devices for tank flotation, 166 
Demolition charges, self-propelled am¬ 
phibious, 170-171 
Demolition vehicle, 266 
Desiccating devices for anti-fogging, 310 
Detection of torpedoes, sonar, 251 
Displacement-length ratio, amphibians, 
190 

Division 12 NDRC, organization and 
operations, 1-5 

Driver vision, amphibians, 194 
Douglas Aircraft Co., Inc., 288 
Drexel Institute of Technology, 198, 213 
Drogues for antitorpedo nets, 251 




359 




360 


INDEX 


Drones for delivering 10-ton bombs, 332 
DUKW; advantages, 6, 88, 109, 184, 186 
combat performance; European The¬ 
ater, 90-93 

Mediterranean Theater, 84-90 
Pacific Theaters, 93-106 
Southeast Asia Theater, 106 
components; A-frame, 42, 66 
anchor, 33 
armament, 52 
bilge pump, 23 
brakes, 29 

cooling system for engine, 26 
drain valve, 25, 66 
engine, 20 

ferrying equipment, 44, 166 

foam suppressors, 328 

freeboard,188 

heating system, 27 

hull, 19, 184 

landing mats, 50 

lifting and mooring eyes, 32 

load pallets, 42 

lubrication provisions, 26 

ordnance, 109 

propeller drive, 21-22 

propeller guard, 134 

rocket-launching installations, 274 

rudder, 23 

superstructure, 30 

surf protection equipment, 30 

tires, 27 

tractor-trailer, 50 
trailer, projected, 50 
transfer rigs, 43 
transmission, 38 
water seals, 26 
winch, 32 

design limitations, 107 

history of development, 11-15, 66, 67 

maintenance, 33, 81 

operating manual, 75 

performance tests, 53-63 

production, 106 

recommendations for improvement, 
11, 38, 67-69, 106-113 
specifications, 35, 183-197 
techniques of use; airplane-ferrying, 
48 

cargo stowage, 76 

casualty evacuation, 77 

command system, 77 

discharging ships, 13 

ferrying, 165 

in surf, 38, 55-59 

logistical techniques, 13, 65, 76-79 

losses due to mud, 87 

on coral reefs, 37 

on land, 35-41 

river crossings, 90, 93 


speed in water, 38 

tactical techniques, 13, 65, 79-81, 

324 

tank-ferrying, 44-47 
training program 70-81 

Egg (10-ton bomb), 332 
Electric generator, ultrasilent gasoline- 
driven, 336 

Eliason toboggan, 116, 322 
Ellice Islands, use of the DUKW, 97 
Engine used for DUKW, 20 
Engineer ponton device for tank flota¬ 
tion, 165 

European Theater, use of the DUKW, 
90-93 

Ferries; 30-ton tank ponton ferry, 214 
90-ton tank ponton ferry, 221 
Ferrying with DUKWs, 44-50 
Firestone Tire and Rubber Co., track 
design for the Weasel, 121 
Flotation devices for tanks, 165-168 
Foam suppressor for wake suppression, 

325 

Food Machinery Corp., 12, 172 
Ford model amphibious jeep, 6 
Formulas for load reactions of ponton 
bridges, 198-212 

Fort Story demonstration of the DUKW, 

59 

France, Southern, use of the DUKW, 89 
Freeboard for amphibians, 188 
Funafuti demonstration of DUKWs, 62 

Geer moisture-absorbing film, 311 
General Motors Corp., 12, 275, 278 
Generator, silent gasoline-driven elec¬ 
tric, 336 

GMC 270 engine, 20 
Goodrich Co., If. F., 301 
Goodyear tire, 297 
Grasso wheel, 297 

Ground clearance of amphibians, 189 
Ground-up designing for amphibious 
vehicles, 179-181 

Guadalcanal demonstration of DUKWs, 

60 

Guided missile, 10-ton, 332-335 
Gun carriages, amphibious, 151-154 
Gun carriages, reduction of bouncing, 
283 

Gun mounts for tanks, 267 

Hale device for tank flotation, 165 
Hayes muffler (for tank noises), 279 
Heating system, DUKW, 27 
High way trestles, 220 
Howitzer transportation by DUKWs, 79 
Hull, amphibian, 184 


Hull design, DUKW, 19 
Hull design of ships, 314 
Hydraulic pumping system for Baker 
tank, 260 

Hydraulic Research Institute, Univer¬ 
sity of Iowa, 316 

Improvements recommended for the 
DUKW, 11, 38, 67-69, 106-113 
Improvements recommended for the 
Turtle, 263 

Improvements recommended for the 
Weasel, 149 
Infrared devices, 336 
Inglis bridge, 216 
1-T-E Circuit Breaker Co., 289 
1VI tank, 254-256 
I wo Jima, use of the DUKW, 102 

Jacobs Co., F. H„ 312 
Jagger 1926 amphibian, 180 
Jagger Honukai, 180 
Jeep, amphibious, 6 
Jeep flotation, 168 

Jeep performance in snow, 118, 130 
Jet-propelled amphibious vehicles, 177— 
179, 197 

Jones and Lamson Machinery Co., 292 
Joor tire, 298 

Jumping system for land combat ve¬ 
hicles, 263 

Knox tire, 297 

Kwajalein, use of the DUKW, 98 

Lacquer coatings for anti-fogging, 309 
Land combat vehicles; demolition ve¬ 
hicles, 266 
design criteria, 253 
light tank (Baker), 257 
medium tank (IVI), 254 
Turtle, 253-266 

Landing mats laid by DUKWs, 50 
Landing pier, 229 

Landing ship for amphibious tanks, 230 
Leyte, use of the DUKW, 101 
Lifeboat and raft, airborne, 301, 304 
Load capacity, amphibians, 189 
Load effects on ponton bridges, 198-212 
Loading and unloading amphibians, 194 
Logistical techniques for the DUKW, 
13, 65, 76-79 
Loir Rain Repeller, 306 
Louisiana swamp buggy, 118 
Lubrication for the DUKW, 26 
LVT track propulsion, 172-177 

M 29 Weasel; design, 132-135 
military use, 141-145 
recommendations, 149-150 





INDEX 


361 


M-29C Weasel (Ark); design, 135-140 
military use, 145-149 
recommendations, 149-150 
Machine gun accessories, 271 
Machine gun mounts, 269 
MacLean tire, 298 
Magnetic compass for tanks, 336 
Magnetic torpedoes, nets for, 249 
Maintenance of DUKW, 81 
Maneuverability of amphibians, 194 
Manhattan Project, Div. 12 personnel 
with,336 

Map reproduction devices, 336 
Marianas Islands, use of the DUKW, 98 
Marmon-Herrington model, amphib¬ 
ious jeep, 6 

Marshall Islands, use of the DUKW, 98 
Martin elastic spoke tire, 298-300 
Mediterranean Theater, use of the 
DUKW, 84-90 

Merchant vessel protection against sub¬ 
marines, 239-252 

Messina Straits, use of the DUKW, 86 
Missile, 10-ton guided, 332-335 
Mobile rocket launchers, 274 
Mooring system for DUKWs, 76 
Mud and sand operations with amphib¬ 
ians, 177, 195 
Muffler, tank, 279 

National Research Corp., 305 
Nelson muffler (for tank noises), 279 
Neoprene tire spoke, 300 
Net defense against torpedoes, 239-249 
New Guinea, use of the DUKW', 95 
Night bombing defense with flares and 
haze shells, 336 

Noise-reduction for tanks, 278-283 
Normandy, use of the DUKW, 90 

Observation devices for tanks, 269 
Odograph, 336 

Okinawa, use of the DUKW. 104 
Omaha Reach, use of the DUKW, 91 
Optical surfaces, anti-fogging treat¬ 
ments for, 308 

Paddy vehicle, 155 

Palau Islands, use of the DUKW, 100 
Palletized loads for DUKWs, 42 
Panoramic observation devices for tank 
turrets, 269 

Peleliu, use of the DUKW, 100 
Pelican (6-ton amphibious vehicle), 158 
Philippines, use of the DUKW, 101 
Photography, underwater, 252 
Piers, portable, 229 

Plexiglas shields, use with rain-repel¬ 
lents, 306 

Pneumatic life raft, 301 


Pneumatic tire substitutes, 296 
Ponton bridges; for 30-ton tanks, 214 
for 60-ton tanks, 215 
load reactions for articulated types, 
203-213 

load reactions for continuous types, 
198-203 

Ponton ferry, 221 
Pontons for the jeep, 168 
Pontons for vehicle flotation, 50, 167-168 
Portable bridge, 200-foot, 217 
Portable bridges, Bethlehem Steel Com¬ 
pany, 217 

Portable railway bridge, 220 
Powdered metals for brake lining, 288 
Power consumption of a snow vehicle, 
322 

Probert gun, 257 
Propeller, sine disk, 311 
Propeller drive design, DUKW, 21-22 
Propeller for DUKW, 21,68 
Propeller for shallow draft boat, 311 
Propulsion of amphibians by submerged 
tracks, 172 

Propulsive coefficient, amphibious ve¬ 
hicles, 191 
Protectoscopes, 268 

Provincetown demonstration of DUKW, 
55 

Pump, DUKW bilge, 23 
Pump, Gould “water piston”, 24 

Quay repairs, 230 

Railway bridge, portable, 220 
Rain-repellent coatings, 305-308 
Ramps for bridges, 220 
Recoil reduction system, 265 
Recommendations for improvement; 
amphibious vehicles for soft ter¬ 
rain, 196-197 

DUKW, 11, 38, 67-69. 106-113 
Turtle, 263 
Weasel, 149 
Rhino ferry, 223 

Ritchie flotation devices, 165-167 
Rocket DUKW, 53, 80, 275 
Rocket-launching devices, 274 
Rocket-propelled landing craft for 
assault across mud, 177 
Roebling Alligator, 180 
Rudder design, DUKW', 23 
Rust prevention on DUKW, 68 
Rvukyus, use of the DUKW, 104 

Saipan, use of the DUKW, 98-100 
Salerno, use of the DUKW', 87 
Salvaging with DUKW's, 78 
Saskatchewan Glacier, snow studies, 319 
Scorpion (mobile rocket launcher), 274 


Scout car, German, 180 
Screw propelled snow vehicles, 118, 119, 
322 

Seals against water in amphibians, 25 
193 

Shearing strength of snow, 318 
Ship turning research, 314 
Sicilian invasion, use of the DUKW, 84 
Silica gel dryer for anti-fogging, 310 
Silicone mixtures for water-repellent 
coatings, 306 
Sine-disk propeller, 311 
Snake project (amphibious demolition 
charges), 170-171 

Snow; penetration by vehicles, 318 
physical characteristics, 318-319 
setting mechanisms, 323 
types, 317 

vehicle performance in, 320-324 
Snow tractor, M7 (Tucker Sno-cat), 117 
Snow vehicles; see also Weasel 
Aero-Sled, 117, 130, 322 
Bombardier, 117, 130, 322 
performance, 320-324 
Tucker Sno-Cat, 117 
Society of Automotive Engineers, 287 
Solomon Islands, use of the DUKW', 93 
Sound-absorbing lining in tanks, 280 
Southeast Asia Theater, use of the 
DUKW, 106 

Sparkman & Stephens bridge, ramp for, 
220 

Sparkman & Stephens, Inc.; amphibious 
devices, 158, 165 
DUKW problems, 12, 74 
ferries, barges, and bridges, 222, 236 
gun carriage design, 151 
life rafts and lifeboats, 301, 304 
LVT track propulsion, 172 
paddy vehicle, 155 
rocket-propelled landing craft, 174 
sine-disk propeller, 312 
Specifications; amphibious vehicles, 183— 
197 

DUKW', 35 
Turtle, 253 
W'easel, 115, 117, 125 
Speed-length ratio, amphibians, 190 
Spring suspension for gun carriage, 286 
Sprocket noise in tanks, 278 
Stability of amphibious vehicles, 192 
Stevens Institute, 6, 16, 314 
Studebaker Corp., 120 
Surf ability of amphibians, 193 
Surf performance of DUKW, 38 
Surf protection on DUKW, 30 
Swamp buggy, 118 

T-15 Weasel; design, 117-123 
military use, 140-141 







362 


INDEX 


pilot model, 125-131 
production model, 131-132 
recommendations, 149-150 
tests, 123-125 

T-24 Weasel; see M-29 Weasel 
Tactical uses of the DUKW, 13,65,79-81 
Tactical uses of the Weasel, 143 
Tank ferrying barge and transport ves¬ 
sel, 222 

Tank landing ship, 227-229 
Tank towing tests on LVT, 172 
Tanks; amphibious transportation of, 
44, 214-230 

components; air cleaner for engine, 
272 

assist-feed for guns, 271 
flotation devices, 165-168 
gun mounts, 267 
magnetic compass, 336 
protectoscope, 270 
turrets, 254 
viewing devices, 269 
design; light tank (Baker), 257 
medium tank (IVI), 254 
engine starting in cold weather, 313 
noise reduction, 278-283 
protection against land mines, 336 
specifications, 253 
Tarn, T. R„ 221 
Tectyl rust preventative, 288 
Terrapin, British, 180 
Thread gages, automatic, 292-296 
l ire inflation system, DUKW, 28 
Tire substitutes, non-resilient, 297 
Tire substitutes, resilient, 298 
Torpedo, radio-controlled aerial, 336 
Torpedo detection, sonar, 251 
Torpedo Net Defense, 240 


Torpedo protection for merchant ves¬ 
sels, 239-252 

Towing vessels for tank-ferrying barges, 
224-227 

Track-laying amphibians, 114-150 

Tracks for water propulsion, 172-177 

Tractor, caterpillar, 118 

Trailer hitch, amphibious, 168-170 

Trailers, amphibious, 164 

Training program for DUKW, 70 

Treadway bridge, 218 

Trestles, portable, 215, 220 

Trim of track-laying amphibians, 195 

Truck, l^-ton amphibious, 6 

Tube bridge, 216 

Tucker Sno-Cat (M-7 Snow Tractor), 117 
Turning circle of ships, 314 
Turret mock-ups, 272 
Turret seat, 271 
Turtle vehicles, 253-266 
air transportation of, 263 
anti-recoil system, 265 
jumping system, 263 
light tank design (Baker), 257 
medium tank design (IVI), 254 
recommendations for improvement, 
263 

specifications, 253 

Underwater photography of TND net 
operation, 252 

United Shoe Machinery Corp., 254, 267 
United States Forest Service Snow- 
Motor, 116 

Utah snowmobile, 116 

Viewing devices for tanks, 269 
Vinylite, shields for use with rain- 
repellents, 306 


Vision block, 152. 194 

Wake visibility suppression, 324 
\V ater-absorbent films for anti-fogging, 
310 

Water-repellent coatings, 305-308 
commercial plastics, 306 
dry application, 307 
durability tests, 306-307 
nitrogenous bases, 306 
paraffin wax, 305 
recommendations, 308 
silicone mixtures, 306 
soaps, 305 

tetra-alkyl tin compounds, 306 
wet application, 307 
Water-tightness of amphibians, 25, 193 
Waves in the ocean; characteristics, 327— 
331 

effect of wind velocities, 327 
Weasel; Model T-15 (M-28), 117-132,140 
Model M-29 (T-24), 132-135, 141-145 
Model M-29C, 135-140, 145-149 
operating terrain, 316 
parachute delivery, 131 
production, 149 
recommendations, 149 
snow performance, 322, 325 
specifications, 115 
track failure, 148 
Weatherhead Co., 310 
Wetting agents for anti-fogging, 309, 310 
Wind and wave studies, 327 
Windshields, anti-fogging measures, 308 
Woods Hole Oceanographic Institution, 
325 

Yagow devices for tank flotation, 166 





























































































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